B3 Removing waste water safely

B3.5 Dry toilets

Dry toilets do not use water and can be useful where water supply is extremely limited. There are two types of dry toilets: pit toilets with waste going directly into a hole in the ground or pit, and composting toilets where waste goes into a sealed container or cavity installed above the ground or in the ground. A dry toilet can be a useful addition to a flush toilet for crowded households. Dry toilets do not usually dispose of grey water.

The advantage of a pit toilet is that it is cheap to construct, requires little maintenance and has no moving parts. Disadvantages include the need to dig a large hole and to relocate the toilet when the pit is full. In high rainfall areas with a high water table, the pit will need to be lined to avoid collapse, can fill up with water, may smell and may pollute the water supply.

Composting toilets cost more to build and require regular maintenance. However, a composting toilet that is well constructed and sized to match the house population will not produce much odour and can be used for many years. Since composting toilets are located above a compost container, this often requires stairs and can make access difficult for people with limited mobility.

As with any other toilet, dry toilets need toilet roll holders, privacy locks, light, good ventilation, and a high shelf for toilet roll storage. A hand washing point should be provided near the dry toilet to prevent the spread of disease. Survey data show that five per cent of surveyed houses had a dry toilet.

Design and specification

When specifying and installing a pit toilet, ensure that:

• it is located away from water courses and bores, check local building regulations for recommended distances from a water source, but as a guide a minimum of 100m is recommended
• the bottom of the pit is above the highest water table level
• the pit is fully lined if it is close to a bore or water course or if there is a high water table
• the pit is well vented, drawing air into the pit through the toilet bowl and exhausting air via a dark coloured pipe exposed to the sun that will act as a thermal chimney extending above the roof line, to ensure smells are taken away.

When specifying and installing a composting toilet, ensure that:

• the residents are comfortable with the idea of emptying the chamber and disposing of the compost material, and that this does not conflict with any cultural beliefs
• the type and size of toilet is suited to the household population and expected fluctuations in usage
• the residents have the resources and skills to undertake necessary maintenance
• if the toilet requires a fan, electricity is available
• there is enough space under the building to install, access and maintain the compost chamber.

When specifying any dry toilet system, ensure that:

• it is conveniently located for use by residents
• it is down wind of living areas
• it has natural and electric lighting
• there is adequate natural ventilation
• a locking door, toilet roll holder and shelf are provided in the cubicle
• hand washing facilities are provided near the toilet
• the pit or chamber and vent are protected by fly screens.

Consider:

• building a path between the house and the toilet, which is slip resistant and accessible to people with disabilities
• using a self-closing toilet lid, to provide more protection against flies
• designing the cubicle to comply with AS 1428.1 Design for access and mobility, and locating the hand washing point that can be accessed by people with disabilities
• providing the capacity to install grab rails in the future.

 

Quality control

 

During construction and before making the final payment, check that:

• the toilet and cubicle are built as specified
• the composting toilet has been installed to the manufacturer’s requirements and a certificate has been provided
• there is access to the composting chamber for maintenance
• it is not possible for stormwater to enter the pit or container
• the toilet pan and lid are stable and secure
• the toilet roll holder and shelf are securely attached to the wall
• there is a hand washing point nearby
• if specified, the installations are accessible for people with disabilities.

Maintenance

 

As part of cyclical maintenance, check that:

• the pan does not move when pushed gently from side to side
• the door and privacy locks are secure
• the toilet roll holder is secure
• fly screens are intact and preventing access for insects or vermin
• there is a water supply to the hand basin.

 

As part of cyclical maintenance:

• move the pit toilet every five to 10 years, depending on the level of use
• empty the waste container of a composting toilet regularly, most systems require emptying every 6  to 12 months.

 

Survey data

Septic systems and on-site waste disposal	Percentage of houses	Total houses surveyed
In-ground pit toilet	2%	1,961
Contained composting toilet	3%	1,961

 

Standards and references

Martin, M. 2004, Waterless Composting Toilets, Bush Tech #23, Centre for Appropriate Technology, Alice Springs

Martin, M. 2003. Pit Toilets, Bush-Tech 15, Our Place Magazine. Centre for Appropriate Technology, Alice Springs

Martin, M. 2002. Choosing the right toilet, Bush-Tech 15, Our Place Magazine. Centre for Appropriate Technology, Alice Springs

Khalife, MA, Dharmappa, HB & Sivakumara, M 1998, “An Evaluation of Septic Tank Performance in a Remote Australian Village Provides Insight for Optimizing Onsite Treatment Systems”, Journal of Water Environment Research, Edition 4, Volume 10, USA, Water Environment Federation, pp 33-36