By Umar Nsubuga
Handling foul water and sewerage on sites is a big challenge. Many developers struggle to get it right. With limited piped water and more people buying land in swamps and wetlands, management of sewage becomes a challenge.
Abdu-Wahab Nyanzi, an architect at JR Consultants, says many developers take the issue of sewage for granted, until something wrong happens.
Nyanzi says the ideal case should be for the municipality, town council or local authority to provide a central sewerage system, to which every building connects. This system must end up at a treatment plant that makes use of the solid waste and the water that flows with it.
The real situation
In Uganda, few areas are linked to the central sewerage system. Property growth has opened up many residential areas, but with no supporting sewerage systems.
As a result, most home-owners have to manage their sewage on site. Nyanzi says on-site sewage management involves the use of a septic tank and a soak pit. The septic tank is used to collect and break down sewage into sludge and water.
Nyanzi adds that in cases where there is not enough space, septic tanks are used and regularly emptied when nearly full.
A proper drainage increases house stability and alleviates dampness
According to Nyanzi, it is good practice to use an on-site drainage, so as not to mix waste from the shower or soapy water with waste from the toilet.
Nyanzi says it is against public health rules to drain kitchen waste into the same system as toilet sewerage lines.
It is, therefore, advised that kitchen waste is drained into a separate pipe line and a soak pit.
“All man-holes should be airtight to avoid foul smell and to ensure decomposition in the septic tank,” he advises.
“You must have a vent pipe at the highest man-hole to avoid air locks and back flows.”
There are two drainage systems that are required in a home. The foul water drainage and the rain water drainage systems.
The foul water is what comes out of your sinks in the kitchen and bathroom. The gutters are for rain water. If one drainage system is left for the toilet and foul water, there is a danger of the septic tank over flowing often.
Many areas in Kampala have poor drainages, probably because most have a poorly designed drainage system.
If water is not properly drained away from a foundation, it will pool around the outer foundation and contribute to a condition known as heaving.
A proper drainage increases stability of the ground and alleviates dampness in the basement.
Building in a wetland
If you have a plot in a wetland, many things should be done. You have to raise the ground floors and it is also good to use hard core.
You can also create French drains around your plot. It will be good to fill all the trenches with hard core and cover them with soil.
Clogged gutters cause water to spew over and overflow. This can accumulate around the foundation of the home. Improperly angled downspout drains can also cause water to drain around the foundation of the house.
What can go wrong?
Nyanzi says if foundations are not properly drained, they can easily collapse.
The risk is higher in foundations that form the basement or go-downs. Poor drainage around foundations can cause continuous dampness in the house.
“The floor keeps pushing water or moisture to the surface. As a result, you find water accumulating under carpets, furniture and other household items on the floor”, Nyanzi warns. When the wall is damp, it can