The Enviro Loo is a "dry or waterless sanitation system" rather than a composting toilet. However, we do refer to "composting" in reference to the system, as it is a term commonly associated with this form of sanitation technology. The form of treatment and stabilisation achieved within the Enviro Loo is more of a dehydrating process over a lengthy retention period, with an ancillary, lesser composting process.
Step 1: Liquid is separated from solids
Faeces and urine drop directly through the ceramic toilet pan onto a sloping reception area known as the drying plate. There are a number of ridges along the width of the plate, designed to slow the progress of the solid waste down the plate in order to ensure constant aeration, thereby stimulating the evaporation of liquid and a reduction in volume.
The urine trickles through drainage holes in the front portion of the drying plate and proceeds by gravity to the liquid trap at the bottom of the tank.
Urine from the Enviro Loo is free from flush liquid and therefore massively reduced in volume. The urine produced by one individual per annum is about 500 litres whereas the flushing liquid in a water borne system would amount to 15,000 litres for one person. It also contains a high concentration of nitrate and phosphorous. As such, it requires no treatment before passing into the Enviro Loo System, and is easily dealt with by the system itself.
Step 2: Solid waste migrates down the drying plate
A bed of organic material including enzymes – contained in the Enviro Loo starter pack and added on commissioning of the toilet – covers the drying plate. This organic additive helps kick-start the decomposition process.
Any foreign material such as sanitary pads moves along with the solid waste. Toilet paper ultimately breaks down while newspaper and other foreign materials merely dehydrate and are easily removed from the collection area.
At various times the waste might contain evidence of maggots, larvae and grubs, which are all part of the breakdown and stabilisation process. As the dehydrating material gradually moves towards the collection area, the microbiological activity will begin to slow down due to a lack of moisture.
Slowly but surely the solid waste moves down the sloping drying plate. This movement can be assisted by manually raking the waste from time to time and it is recommended that this task be performed on a regular basis.
Step 3: Dried solid waste is removed
In order to avoid contamination of the dried waste, the waste material is periodically removed from the drying plate collection area and deposited into a hanging drying bag which is placed under the vent pipe. This waste can remain in the bag for approximately six months prior to removal from the system.
The time frame (retention period) from entry of the solid waste to the removal of waste from the collection area, depends on the number of users per day as well as the local climatic conditions namely: average wind velocity, ambient temperature and humidity levels.
No, "grey water" must be processed via its own system.
The following serves to demonstrate how urine and grey water can be treated to ensure an overall zero discharge system in conjunction with the Enviro Loo sanitation system, even where limited ground space is available.
This assumes that there is no existing on-site grey water disposal system or mains reticulation available to divert the urine from an Enviro Loo.
Source of domestic liquid waste streams:• Urine from the Enviro Loo is already dramatically reduced in volume, as it contains no flush liquid. It is important to note that 90 % of all the nutrients of nitrate and phosphorus is in solution and therefore much easier to deal with. Much of the volume of liquid in the Enviro Loo system is lost to the atmosphere through evaporation, which concentrates the liquid waste even further.
• Kitchen liquid waste contains fats, grease, detergents and food that will need to be removed by a fat trap before entering any system.• Bathroom liquid waste needs to filter through a hair trap and then an arrester tank, which will deal with the rapid inward flow of (for example) a full bath being emptied. This will ensure that the system is not flooded. The arrester tank is a gravity fed receptacle of approximately 150-litre capacity, with a hair filter that accepts the flow from the bath in a 50 mm pipe but the outflow is governed to an approximate flow of ten litres per minute. The overflow liquid from the Enviro Loo can be added to and diluted by this waste stream.
The urine and grey water enter a common waste duct in the form of a concrete lined trench:
• The bottom third of the trench is filled with stones. This helps with aeration and is a base for algal growth, which in turn feeds on nitrate and phosphate and becomes the biomass feedstock of the sludge particles in the liquid waste stream.
• A combination of soil and compost covers the stone layer.
• A variety of grass known as Vetiver – which is indigenous to many countries - can be planted over this layer. Figures published show that a "take up" of nitrate from an incoming flow of 3 to 4 mgm concentrate per 100 ml reduces to about 0.6 mgm per 100ml within two to three days. At the same time a considerable volume of the moisture will transpire into the atmosphere.
The effluent from this trench then passes into a bed containing trees, which act as a transpiration bed. These could be fruit bearing trees or other known varieties that consume large quantities of water. At night trees absorb carbon dioxide and give off oxygen but they also transpire large amounts of moisture through the leaf stomata. Some trees have the potential to transpire in excess of 600 gallons of water every twenty-four hours. The trees should be bordered with a bed of Vetiver grass, which would act as a final absorber of any excess nitrate and phosphate. These roots are known to grow down to a depth of 3 metres, which would be an adequate safeguard for nutrient absorption and moisture transpiration. Another added advantage of this grass is that it can be harvested as a base material for grass weaving, similar to cane weaving.
NOTE: The dimensions of this trench will vary depending on the: -• flow and number of people involved
• the geological conditions
• the contour levels of the site.
The Enviro Loo's liquid level indicator makes it easy to see when the level of liquid approaches the drying tray.
Without favourable contour levels, gravity flow is not achieved and pumping of the residual urine would have to be undertaken to transport it into the trench at the base of the arrester tank. However this pumping would only be of a periodic nature and would be determined by the number of daily users.
The waste liquid would be accessed via the external Enviro Loo inspection hatch and through the drying tray where a service hole is provided for this purpose. This task can be accomplished with an electrical or manual pump. This would not arise with the DCRX model, as the urine in this unit is diverted from the system at the point of entry, which is above ground level.
The emergency urine low pressure one way overflow connector is sold as an optional item. The standard Enviro Loo is generally a "zero discharge" system without the need of an overflow connector, however, one could be installed based on one or more of the following reasons:
• potentially high user numbers above the recommended levels per unit/model
• adverse climatic conditions with regards to the potential evaporation rate
• shaded areas limiting direct sunlight and wind
• ensuring favourable aerobic conditions at all times even when subject to abuse or misuse
• reducing the potential need to pump or remove excess liquid.
As only urine and not "black" water is being diverted there are a number of recommended ways of installing the overflow connector:
• directly into the soil as a soak away or into a transpiration bed provided there are favourable ground conditions
• if available, connected into the on-site grey water reticulation
• if neither of the above are viable options then diversion into a holding tank for later pumping and safe removal from the site
The local ground conditions should dictate the best possible connection option. In the case of an overflow being connected to an Enviro Loo, it must be remembered that evaporation by wind and sun still remain the primary function. The overflow connector merely performs a secondary function when required, and generally for a limited time only.
Both urine and faecal waste contains "pathogens", a specific group of bacteria capable of causing disease. The Enviro Loo is designed to destroy these harmful pathogens without the aid of additional liquid or chemicals.
These are a specific group of bacteria capable of causing disease, as opposed to commensal bacteria, which reside in the body and perform certain functions that are complimentary to the biological process. There are bugs that are capable of making us and other animals sick and there are equally many trillions, which enhance the function within the body.
Types of pathogens: They are many and various, from micrococci, staphylococci, streptococci and many others. They are identified under the microscope as round organisms. Others are cylindrical and spiral. In faeces, one normally looks for bacteria such as e.Coli, coliforms and salmonella. Viruses are also pathogenic.
Faecal pathogens are destroyed due to the prolonged residence time in the unit. Urine contains very few pathogens and these are dealt with by the aeration provided by the plant root structures. The grass roots absorb all the sewage nutrients and assist with moisture transpiration. The roots of the trees would take up the remainder of the moisture.
The fundamental research and development of the Enviro Loo has been conducted over many years and centres on a process called "forced aeration composting". This is a process of encouraging the growth of aerobic bacteria without the use of any chemicals to stabilise organic waste material in an accelerated time frame.
In essence, the Enviro Loo treats human waste in its DRY state by subjecting it to a bombardment of a pulsating air stream, which devitalises all the disease-spreading pathogenic bacteria, without sending it to a sewage works.
The process has a number of advantages:• Air forced into the solid waste contains oxygen, which is a very powerful deodoriser, thereby alleviating the creation of toxic odours.
• The process creates a negative pressure inside the unit that further serves to trap odours.
• In a normal wet sewage treatment plant there is an end by-product of a disagreeable sludge which can be a health hazard and difficult to dispose of.
• In the forced aeration process the end solid product is an environmentally friendly, pathogen and weed free dry stabilised material, high in phosphorus fertiliser, which has a revenue bearing possibility.
• The composting process can be reduced from approximately four months to only twenty-one days.
• The process is far more economical than normal sewage treatment and can be maintained by relatively unskilled labour.
The ventilation system aids aeration.
As the waste moves down the drying plate it is constantly subjected to a large airflow. For example with a relatively low wind speed of 4 kilometres per hour we can estimate airflow of approximately 100 to 150 cubic metres per hour through the system. This continual airflow has the following effect on the solid waste:
• A reduction in volume through evaporation of the high moisture content
• The oxygen devitalises the pathogenic organisms
• The oxygen acts as a deodorising agent
Biological heat aids dehydration.
In the course of the composting process, there is a build-up of heat within the mass of the composting material. Temperatures of up to seventy degrees Celsius can be reached particularly with "forced aeration composting". The "composting" occurring within the Enviro Loo raises temperatures to 55 degrees Celsius and above (when measured directly underneath the sealed inspection cover). Within the solid mass on the drying plate the internal temperature would never go above forty degrees Celsius for the following reasons:
• The solid mass on the drying plate is too small to retain heat
• Any heat build-up is quickly dissipated by the incoming air
• Reducing the in-flow of air could result in anaerobic conditions within the system.
Radiant heat therefore contributes to the operation of the system via the heat build-up underneath the inspection cover and through the approximate ten degree increase in temperature (above ambient) within the ventilation pipe. This causes a convection current which assists the operation of the ventilation extractor and ensures positive ventilation extraction through the system.
There are two very basic and specific groups of bacteria, namely aerobes and anaerobes. Aerobes require oxygen as part of their metabolism whereas oxygen destroys anaerobes, which exist in an atmosphere that is devoid of oxygen.
The oxygen in the Enviro Loo's airflow kills off the anaerobic bacteria in a process known as devitalisation. This same oxygen encourages and promotes the activation of the formation of aerobic bacteria, which in turn digests the solid mass into a compost-like material. This leads to the stabilisation of the organic waste.
No, the Enviro Loo operates without the use of chemicals.
After installation and at the time of commissioning, a small amount of organic compost and a sachet of enzyme material are deposited into the unit via the toilet pan.
This assists with the initiation of the aerobic bacterial process after the Enviro Loo is first used. The underlying technology is a three-phased promotion of the formation of aerobic bacteria. The faeces leave the large intestine and at this stage the bacterial content of the solid waste is mainly anaerobic, bacteria that thrive without oxygen. The biotechnology of the Enviro Loo stabilises and breaks down the solid waste by the generation of aerobic bacteria. These aerobes are also capable of devitalising pathogenic bacteria. Promoting the generation of aerobes leads to the demise of the anaerobes, which create odour.
In essence the Enviro Loo technology aims to create within the unit an aerobic environment as soon as possible in order to begin the stabilisation of solid waste and neutralisation of any noxious odours. Oxygen is a very powerful deodoriser.
• Addition of the compost creates a "bed" onto which the faeces comes to rest.
• The compost allows a circulation of air under the faeces.
• A natural component of compost is not only aerobic bacteria but also many other microscopic organisms that will digest human solid waste.
• The enzyme also promotes the breakdown of the faeces.
Hence the combination of the compost and the enzyme facilitates and "kick starts" the initial treatment of the solid waste that enters the system. It is a "one off" requirement.
A few handfuls of additional compost added after the unit has been subjected to heavy use will improve the efficiency of the process but is not essential.
Compost is organic fertiliser.
Enzymes are catalysts and are protein in composition, facilitating biochemical reactions within the body.
By the time it becomes necessary to remove solid waste from the Enviro Loo there is little chance of infection. The only risk is if new material is mixed with the more mature material.
The prolonged dehydration process and retention period results in bacteria attenuation and devitalisation, and microbiological analysis proves that the number of surviving pathogens is almost nil - the international standard allowable per gram of waste material by Health Authorities is 250 organisms. The highest number ever found in samples taken from the Enviro Loo and tested by the internationally accredited Cydna Laboratories was 30 organisms of e coli. This is well below the allowable limit [see Enviro Loo Waste Analysis below].
By way of illustration, the graph below - Feachem at al (1983) - depicts the elimination of pathogens related to temperature and time.
This demonstrates that at a temperature of approximately 35 degrees Celsius most pathogens would be reduced below hazardous level within a retention period of one year. Therefore if the waste has a retention period of between 18 to 24 months, it is very unlikely that disease causing pathogens would survive at infective concentrations, apart from helminths (various parasitic worms such as tapeworms and flukes). Viruses from human waste will not survive outside the host body for longer than a three-month period. The eggs of ascaris worm cysts and other helminths are however capable of extended periods of survival at temperatures below 65 degrees Celsius.
Ascaris worm cysts (helminths) are spread in faeces and can endure for long periods by the formation of a hard coating around the egg. They are difficult to kill under normal circumstances. Since the temperatures reached in an Enviro Loo are not a sufficient guarantee for the destruction of the cysts, solid waste is transferred to the drying bag under the vent pipe for 6 months. Here the contents are subjected to temperatures of about 65 degrees Celsius, which is enough to destroy any surviving ascaris cysts, prior to removal from the unit.
Bacteria require moisture in order to exist and multiply. Moisture levels below 20% in any material make it difficult for bacteria to survive. Testing moisture levels is a quick and easy way to determine the likelihood of pathogenic bacteria being present in any sample.
Although there are countless and many varieties of disease causing bacteria, the above three mentioned are used as an International standard.
We recommend wearing protective clothing, a mask and rubber gloves when handling dried material and removing it from the unit. Preventative vaccinations against Hepatitis A & B are also advised.
Some Local Authorities/municipalities specify where human waste can be disposed of . When removing waste it is necessary to comply with the Local Authority regulations. For example, certain municipalities stipulate that when removing waste from an Enviro Loo all foreign matter such as bottles and cans be disposed of at a landfill site. The dried faeces is sent to the post treatment sludge side of a treatment plant. Other districts (generally rural) have no fixed policy and in such cases the waste is either buried on-site in a suitable area or incinerated.
Nutrients do not evaporate but remain within the Enviro Loo tank.
In the case of diverting the urine from the unit, at the rate of approximately 1.2 litres person per day, the nutrients from this urine do not enter the soil as a pollutant, but are directed to the roots of grass, trees or shrubs. A small tree might transpire as much as 100 litres per day. This effluent liquid is absorbed into the plant root systems where the nutrients and water are used in the growth of the plant.
Any excess water is transpired out through the stomata in the plant leaves. In addition the leaves of the plant absorb carbon from the atmosphere in the form of carbon dioxide. The carbon is used and the remaining oxygen is returned to the atmosphere.
So the whole process is a natural environmental cleansing technology!
It's possible for a small amount of faecal material to drop down into the urine.
The liquid within the Enviro Loo has a long residence time in the unit. Pathogen bacteria from the faeces cannot survive for very long in the tank where it is subjected to forced flows of oxygen.
No, because there are too many factors (examined in the following question) that influence evaporation.
It's important to remember that although there is scientific information that relates to the evaporation of water in various circumstances and environmental conditions, the liquid in an Enviro Loo is not water. Urine is a liquid solution of various chemicals, which are both organic and inorganic in nature, all of which vary from person to person.
Even the evaporation of plain water is a very complex reaction that is extremely variable depending on the prevailing climatic conditions. The evaporation of a salt solution is even more complex.
When water evaporates it needs 540 calories per gram of energy to break the bonds between water molecules in order for them to move freely and evaporate. The hotter the water the higher the rate of evaporation.
Air pressure affects the diffusion rate, which affects evaporation. There is a further complication in that there are different convection rates in both the water and the air as the temperature varies which will affect the evaporation rate. In the case of an Enviro Loo the ambient air temperature could be much higher than that of the liquid within the unit tank, situated deeper in the ground.
The higher the flow of air over the surface of the water the greater the rate of evaporation.
The higher the humidity, the lower the rate of evaporation.
The original research and development of the Enviro Loo was carried out in the climatic conditions around Johannesburg, South Africa. Units were later installed at locations representing conditions of desert, semi desert, high humidity, tropical conditions, areas of winter temperatures down to minus 5 degrees Celsius [periodic] and areas of high rainfall. Our research demonstrated that at wind speeds as low as 4 Km per hour the system drew over 100 cubic meters of air over the drying plate per hour. At the majority of locations, provided the designed number of users per day was adhered to, the solid waste dehydration was satisfactory over the long term, as was the rate of evaporation.
• Positioning of the unit in relation to available direct sunlight
• Number of daylight hours
• Shaded hours by cloud cover
• Shaded hours by trees or other buildings
• Temperature achieved during the hours of sunlight
• Wind velocity – ventilation
• Relative humidity, which is complicated by wind velocity and resultant ventilation
• Percentage concentration of solids in the liquid mass
• Complications of evaluating air concentration
• Partial pressure
If there be any doubt in relation to either temperature, wind or humidity levels in the case of the Enviro Loo's operational efficiency, the client should be informed of how this situation can be counteracted [see further below].
The Enviro Loo is designed to operate in almost any climatic situation and will stand conditions of overload for protracted periods. Whereas it will handle solid waste overload at surprising levels, once the liquid waste covers the drying tray, all aerobic activity ceases and an anaerobic situation takes control with the resultant odour problem. The situation can be rapidly reversed by removal of the offending liquid.
The Enviro Loo is driven by two major natural power sources:
• Sun - heats the tank.
• Wind – drives air and oxygen through the system.
In winter there is surprising little difference in the internal temperature at the base of the tank. A metre below ground level, winter and summer temperatures do not vary all that much.
In winter the air drawn into the unit via the inlets is naturally colder. The temporary blocking of the external inlets for the winter months will allow warmer air to be drawn into the tank through the toilet pan and help remedy this situation. Or, if electrical power is available, a suspended light bulb (painted black) in the tank will also improve the internal temperature.
In addition the vent pipe should be insulated with lagging to prevent condensation of the exiting moisture while an electrical or solar-powered fan must be installed and run continuously.
This will drastically reduce the rate of evaporation and can be counteracted by the installation of an electrical or solar-powered fan.
"Zero Discharge Sanitation" means that no harmful effluent re-enters the environment, more specifically the water source, from the sanitation unit.
Since the Enviro Loo loses liquid to the atmosphere by means of evaporation, and solid waste dehydrates and is removed, the system is one of "zero discharge".
No! A septic tank consists of a large divided tank into which the human waste and flushing water is directed. The term for this liquid and solid mix is "black water". After a period of retention in the tank during which a process of some stabilisation occurs, the polluting effluent is allowed to seep from the tank into the surrounding soil.
Pit Latrines are known for polluting ground water in excess of 20 miles or more away through the soil.
The figures below demonstrate that even without any reduction of liquid effluents via evaporation or transpiration, dry sanitation systems would reduce the amount of liquid effluent required by flushing systems, from entering the soil or environment.
Volumes of liquid effluents per flushing systems per person per annum: -
Water borne 15,000 litres Septic 15,000 litres Dry systems (Enviro Loo) 500 litres
The average person will generate approximately 1.37 litres of urine and 0.14 kg of solid waste per day. This equates to an approximate annual amount of: -
Urine 500 litres Faeces 50 kg
Yes, Urine is a very beneficial fertiliser! As a rule of thumb the diluted urine from one human, spread over one square metre, will adequately fertilise a crop from planting to harvest. Present research carried out in some European countries shows a 30 % increase in yield where urine was used to fertilise crops of maize. Urine can contain between three to seven grams per litre of nitrogen and lesser amounts of phosphorous.
Faecal matter generally contains high levels of phosphorous, which can be extracted from dry toilet systems [the Enviro Loo] and also has reasonable (albeit not as rich) soil conditioning properties.
Once it's moved through the system, the effluent from an Enviro Loo can therefore be used as a safe and effective fertiliser. However, only after screening and further treatment by mixing together with other material in an external composting process like for normal garden waste or by forced aeration for a 21 day period.
For a complete overview obtain the proceedings of the Ecosan - Closing the Loop. Conference 7 to 11 April 2003. Lubeck Germany. Contact Person: - Christine Werner Email: - christine.Werner@gtz.de
Liquid Gold. The Lore and Magic of using Urine to Grow Plants. Published in the USA. Green Frigate Books. ISBN: - 0-9666783-1-1.
Tentative Guide Lines for Agricultural use of Urine and Faeces. Bjorn Vinneras. Hakan Jonsson. Email: - firstname.lastname@example.org
The use of Separated Human Urine as a Mineral Fertilizer. Jurgen Simons. Joachim Clemens. Email: - a.Clemens@uni-bonn.de.
Daily cleaning and checking of toilet cubicle
1. Using the provided organic granular Enviro Loo toilet cleaner:
a. Mix approximately a teaspoon into 200ml of water.
b. Dip the toilet brush into this water and clean the ceramic toilet bowl with the dampened brush. This amount of dissolved toilet cleaner is sufficient for cleaning all of the Enviro Loo toilet bowls at each site.
c. Once this task is completed, safely dispose of the remaining cleaner water but not into the Enviro Loo. Depending on the number of visitors per day and the resultant soiling of the bowls, this task could be performed a number of times a day. Any amount of the Enviro Loo toilet cleaner dissolved into water provides a safe organic cleaner and is not harmful if it comes into contact with hands, eyes or mouth. However, if it does come into contact with eyes a slight burning sensation might be felt, in which case wash eyes with water.
d. Under no circumstances should any household or industrial cleaners be used to clean the ceramic toilet bowl nor should they be introduced into the system via the toilet bowl. Introduction of chemicals into the Enviro Loo will be counter productive to the existing aerobic bacteria.
2. Clean and check mounting of toilet seats and re-secure if necessary. In the case of broken toilet seats that require replacing, the Enviro Loo ceramic toilet bowl can accommodate any locally available, standard toilet seat.
3. The cubicle floor and walls can be washed and cleaned with any normal household detergent.
1. Open the rear external inspection cover.
2. Check that the liquid level is below the drying plate and that the system is in an aerobic state of operation i.e. liquids and solid waste are separated by the drying plate. If necessary pump out and remove all liquid from the liquid holding area. This is accomplished by inserting the pump's pipe through the service hole located in the drying plate.
3. If necessary place the already dried waste situated at the rear drying area into the hanging drying bag. If the drying bag is already filled with waste from a previous service, remove from the unit and safely dispose of the dried waste from site. Refill the drying bag with new dried waste from the rear section of the unit.
4. Rake solid waste from under the pan section towards the now open rear end section of the drying plate.
5. Remove any foreign waste from the unit and safely dispose from site i.e. bottles, cans, plastic etc.
6. Lightly cover the raked waste with normal garden compost and introduce 80g packet of fresh enzymes.
7. Add approximately three handfuls of new compost and another 80g packet of enzymes to the front section of the unit via the ceramic toilet pan.
8. If excessive mosquitoes are experienced a cup of chlorine can be added to the liquid holding area below the drying plate. This must be poured into the unit via the service / pump hole situated at the rear section of the drying plate below the open inspection cover.
9. Other alternative materials that can be introduced into an Enviro Loo as a substitute for compost are; agricultural lime, ash, wood chips and any other organic material.
10. Always check and ensure free operation of the wind turbine on top of the external vent pipe.
11. Check and ensure that the entire exterior section of the Enviro Loo and apertures of the two air inlets, are free of debris and vegetation growth.
1. Long handle narrow head steel rake
2. 8mm spanner or socket
3. 3/8th spanner or socket
5. Containers or bags for the safe removal of waste from site
6. Protective clothing
b. Face mask
e. Gum boots
Rotational moulding, which can be defined as a process using heat, biaxial rotation and moulds to produce plastic parts.
Enviro Options only makes use of virgin, linear low-density polyethylene [LLDPE], which is a derivative of the petro-chemical industry.
The additive package which we use in the LLDPE, contains an ultra violet [UV] stabiliser to protect the polymer during outdoor use. The polymer is UV stabilised using a Hindered Amine Light Stabiliser [HALS] and according to testing, which has been carried out [Technical Service Department, Sasol Polymers, Sasol, South Africa] would be classified as a UV8 grade. This translates to use in applications where long term UV stabilisation is required in harsh environmental conditions of high heat and sunlight.
In excess of twenty years. Since the manufacture of the first rotomoulded Enviro Loo in 1993, to date [July 2012] Enviro Options has not had one report of degradation by sunlight.
No, not in it's current configuration.
Only the evaporative urinal tank can be linked to multi storey installations. Please note that in these installations, extension vent pipes and electrical fans would be required. In the case of using an electrical fan, it is possible to adapt the vent pipe flange on the top section and make use of an alternate and smaller sized vent pipe.
There are different individual toilet usage averages available and they vary between 3.25 and 5 usages / flushes per day [United States Geological survey].
Case studies [USA Denver] have shown that flushing frequency [the average number of flushes per household per day] remain essentially unchanged between 1996 and 2005. In 1996 the homes flushed an average of 12.2 times per day and in 2005 they flushed 12.6 times per day.
Women generally spend twice as much time in the restroom as men, with an average of 89 seconds and 39 seconds for men [World Toilet Summit 2008].
There are many differing standards regarding the ratio of toilets required versus the potential number of users. Standards vary from country to country and between regions or states within a country. There are no standards available for alternative or dry systems.
For public ablution facilities, some Consultants use a ratio of fourteen people to one for a flushing system.
Handicap restrooms: - One per 20 regular or at least one per site.
The number of toilets to be provided ultimately depends on the type of application, peak demand and design. Proponents of parity require that the ratio of female restroom facilities are double that of for males.
Note: If alcohol is being served, an additional 15 to 20% toilets / restrooms should be allowed for.