Signs Your Water Tank Needs Cleaning and What to Do Next

Key takeaways

• The four warning signs are a foul smell or taste, cloudy or discoloured water, visible dirt or sludge, and low water flow.
• Dubai Municipality advises cleaning and disinfecting water tanks at least every six months, using approved companies.
• In a 2017 study of 40 household water tanks in Dubai, 18 had bacteria levels beyond accepted standards.
• A proper clean drains the tank, removes sludge, scrubs and disinfects every surface, then refills it. It is also a chance to fix lids, float valves and leaks.

What are the signs your water tank needs cleaning?

Water tanks sit out of sight on the roof or underground, so most people only think about them when something changes at the tap. These four signs are the ones to act on.

1. A foul smell or taste

A musty, earthy or rotten-egg smell, or a stale or metallic taste, usually means water has been sitting with sediment and biofilm (a slimy layer of bacteria) on the tank walls. It is not just unpleasant: it shows something has changed inside the tank.

2. Cloudy or discoloured water

Yellow, brown or cloudy water points to sediment, rust from corroded fittings, or disturbed sludge from the bottom of the tank. Run a tap into a clear glass: if the water stays cloudy, or the colour comes back each time, the tank needs attention.

3. Visible dirt, sand or sludge

Sand in the bottom of a glass, grit in shower heads and tap aerators, or a layer of sludge you can see through the tank's access hatch all mean sediment has built up. Even a thin layer gives bacteria somewhere to grow.

4. Low water flow

Sediment from a dirty tank collects in pipes, filters, aerators and shower heads and slowly chokes the flow. If pressure has dropped at several taps at once, sediment from the tank is one of the first things to check, along with the pump.

A useful check: if your property has a tap fed directly from the mains, compare it with a tank-fed tap. If only the tank-fed water smells, looks cloudy or carries sediment, the problem is almost certainly inside the tank.

Why do water tanks in Dubai get dirty so quickly?

Dubai's climate works against stored water. Rooftop tanks sit in strong sun for most of the year, and warm water helps bacteria and biofilm grow. Fine dust and sand blow in through loose lids, vents and overflow pipes, then settle on the tank floor as sediment.

Research backs this up. A 2017 study led by a Zayed University researcher tested water from 40 household tanks in Dubai and found that 18 of them, 45%, had bacteria levels beyond local and widely accepted international standards. The researchers also found that many residents were not aware of the need to keep their tanks clean.

A dirty tank affects more than water quality. The sediment it sends into the pipes adds to the scale Dubai's hard water already leaves behind, which shortens the life of water heaters, filters, taps and mixers. Read our Water Heater Services page for how this affects geysers.

How often should a water tank be cleaned in Dubai?

Dubai Municipality advises residents to clean and disinfect water tanks and plumbing systems at least every six months, using companies it has approved. Treat that as the baseline, not the target.

Book a cleaning sooner, whatever the schedule, if:

• You notice any of the four warning signs above.
• You are moving into a villa or apartment and do not know when the tank was last cleaned.
• The property has been empty for a long period and the water has been standing.
• There has been construction work nearby, which raises dust levels.
• The tank lid was left open or damaged, letting in dust, insects or birds.

If a property has more than one tank, such as an underground tank feeding a rooftop tank, each one needs cleaning. Cleaning only the rooftop tank leaves the source of the sediment in place.

What does professional water tank cleaning involve?

A proper clean takes the tank out of service, removes everything that has settled in it and disinfects every surface before the water goes back on. The usual steps are:

1. Agree the timing, so the water supply is off when it causes the least disruption.
2. Isolate the tank: close the inlet and outlet valves and switch off the pump.
3. Drain the tank completely and pump out the sludge.
4. Scrub the walls, floor, corners and underside of the lid.
5. Rinse until the water runs clear and all loosened debris is out.
6. Disinfect every internal surface with a disinfectant suitable for drinking-water tanks, and leave it for the required contact time.
7. Flush out the disinfectant, refill the tank and reconnect the supply.
8. Check the lid, float valve, overflow and inlet, and report any cracks, leaks or corroded fittings.

Household bleach, pool chemicals and scented cleaners are not suitable for a drinking-water tank. Ask the company which disinfectant they use before the work starts.

How do you choose a water tank cleaning company in Dubai?

Before you book, ask the company:

• Are you approved by Dubai Municipality for water tank cleaning? Ask to see the approval and check that it is in the same company name as your quote.
• Which disinfectant do you use, and is it suitable for drinking water?
• What exactly is included: draining, desludging, scrubbing, disinfection, refilling?
• How long will the water be off?
• Will I get a written report afterwards, including anything that needs repair?

A clear written quote that answers these questions is a good sign. A verbal price with no detail of the scope is not.

What if the cleaning uncovers other problems?

A tank that has not been cleaned for a long time often has other faults that only show once it is drained: a worn float valve that lets the tank overflow, a cracked or ill-fitting lid, corroded inlet and outlet fittings, or cracks in the tank walls or base.

These are cheapest to fix while the tank is already empty and isolated. Leaking pipework and valves are a job for our Plumbing Works team, and cracks that let water seep into the slab or the ceiling below are a Waterproofing job. Having both trades in one company means one visit instead of three contractors.

For villas, tank cleaning can be added to a villa maintenance plan so it happens on a schedule rather than when someone remembers. See our water tank cleaning service for what we include, or contact us for a quote.

Frequently asked questions