B3 - Removing waste water safely

Waste water in the living environment can make people sick. If people come into direct contact with waste water, or if their water supply is contaminated with waste water, there is a greater risk of transmitting bacteria and viruses that cause disease. These risks are also increased if animals, vermin or insects that have been in direct contact with waste water can pass bacteria on to people.

Removing waste water safely from the house and surrounding living area, treating and managing to dispose of the waste water safely at a community level, is important for people’s health. This section discusses essential items of waste water health hardware in the house and surrounding living area.

Communal waste water systems that take waste water from the surrounding living area and treat it at a central point are discussed in section C3 ‘Waste water’.

Ensure a household waste water disposal system must include the following components:

• a toilet
• drains from baths, showers, hand basins, kitchen sinks and laundry tubs – the floors in all these areas should also have a floor drain and a grate to prevent objects going down the drains and blocking the pipes
• on each drain there should be a water trap or seal, which is a water-filled bend in the pipe under the drain to prevent bad smells spreading from the drain back into the house
• drainage pipes that connect and fall to a main house drain located in the yard, which flows into a system for treating and disposing of the waste water
• inspection openings in the drainage pipes and house drain, for maintenance and removing blockages
• vent pipes that discharge above the roof to remove bad smelling and volatile gases from the drain pipes
• an overflow relief gully for waste water to discharge into the yard and prevent overflow into the house if there is a blockage in the drain pipes.

These components need to be regularly maintained. Approximately 70 per cent of all maintenance money spent by Housing for Health projects over the past 14 years has been spent on plumbing and waste water drainage.

Waste water from houses is described as ‘black water’ or ‘grey water’. Black water is waste water from the toilet. Grey water is waste water from the shower and bath area, laundry area, hand basins and kitchen area. Grey water can account for up to 90 per cent of the waste water from a house. Research¹ has shown that grey water is not the ‘safe’ part of the waste water produced by the house as is commonly assumed. If grey water is not properly collected, treated and disposed of, it may have negative health effects on residents.