Water tank disinfection

The tank is the first place to check when your water smells. Algae and bacteria grow on the inner walls and in the sediment that collects at the bottom, and they pass their odours into the water. Sometimes the smell comes from the supply pipes rather than the tank itself, but any investigation starts with the tank.

There is no single interval that suits every tank, because it depends on the tank's size, location, ambient temperature and daily use. The hot summers speed up bacterial growth, so disinfection at regular intervals is sensible rather than waiting for a visible sign.

Cleaning removes visible sediment and algae from the walls and floor of the tank. Disinfection comes after, and it deals with micro-organisms that scrubbing alone does not remove. Drinking-water tank disinfection combines both steps, because disinfecting a tank that has not been scrubbed first does not give the right result.

You do not have to empty it yourself, but drawing the level down through normal use before the appointment reduces the time needed to empty it at the start of the job. The team agrees this with you when the time is set so you know what is expected.

After the final flush and refill, open a tap close to the tank and let it run for a minute, then check that the water is clear and has no colour or smell. A faint chlorine smell is normal and fades quickly. If the colour does not clear, let us know.

Chlorine tank disinfection is widely used and effective on polyethylene, concrete and fibreglass tanks, but the concentration and contact time vary according to the tank's size and the condition of its walls. That is why the team asks about your tank type and size when you call, before settling on the method.

Any work that opens the water network or changes the supply pipes can let in contaminants such as dust, weld residue or construction materials. If the tank was left empty or open during the work, disinfecting it before resuming normal use is a necessary step.