Your water tank is out of sight, so it's easy to forget about — until something feels off with the water. The good news is that a tank overdue for cleaning almost always gives clear warning signs before contamination becomes a real health issue. Knowing what to look and taste for helps UAE households and building managers act early, rather than waiting for a scheduled service date that may already be too late.
1. The water tastes or smells different
A metallic, earthy or "off" taste, or a musty smell coming from tap water, is often the first and most noticeable sign of sediment, algae or bacterial growth inside the tank. Clean, properly maintained water should be odourless and neutral in taste — any persistent change is worth investigating rather than dismissing as "just the pipes."
2. Cloudy, discoloured or particle-filled water
If water from the tap looks cloudy, has a yellowish or brownish tint, or contains visible particles or flakes, sediment or rust has likely built up at the bottom of the tank and is being drawn into the household supply as the tank empties and refills. This is especially common in tanks that haven't been cleaned in over a year, where sediment layers become thick enough to be stirred up during normal use.
3. Reduced water pressure throughout the property
Sediment and mineral scale don't just sit passively in the tank — they travel into pipes, taps, shower heads and filters over time, gradually restricting flow at multiple points in the system. A noticeable drop in pressure across several taps, rather than just one fixture, often points to tank-level build-up rather than a single blocked pipe.
4. Recurring stomach upsets in the household
Unexplained, repeated digestive issues among people using the same water supply — especially if visitors or neighbours on a different supply aren't affected — can be a sign of bacterial contamination in the tank. This is one of the more serious signals on this list and warrants prompt inspection and disinfection rather than waiting for the next routine service.
5. Visible algae, slime or biofilm on inspection
If a maintenance inspection reveals green or brown algae, a slimy coating on the tank walls, or floating debris on the water surface, the tank is well overdue for cleaning. Warm UAE ambient and roof temperatures let algae and biofilm establish and spread quickly in standing water, particularly in tanks with poor lid sealing that allows light or contaminants in.
6. Insects, sediment or debris around the tank inlet or lid
A cracked, warped or poorly fitted tank lid lets dust, insects and small debris enter directly, contaminating the water regardless of how recently it was cleaned. If you notice damage to the lid, vents or seals during a routine check, treat it as urgent — a compromised tank can become contaminated again within weeks of cleaning.
7. It's simply been too long since the last clean
Even with no obvious symptoms, tanks should be cleaned on a routine schedule rather than waited on until a problem appears — we cover exactly how often in our guide to how often you should clean your water tank in Dubai. If you can't remember the last time your tank was serviced, that alone is reason enough to schedule an inspection now, independent of any symptoms.
Frequently asked questions
Is discoloured tap water always a tank problem?
Not always — it can also come from ageing pipework or a municipal supply issue. But if discolouration appears consistently across multiple taps and doesn't clear after running the tap for a minute, the tank is the most likely source and should be checked first.
Can I clean a rooftop water tank myself?
Basic external checks (lid condition, visible leaks) are fine to do yourself, but full cleaning and disinfection requires safely entering or accessing a confined tank space, proper drainage, and food-grade sanitising agents at correct concentrations — this should be handled by a licensed professional team.
How quickly can algae return after cleaning?
With a properly sealed lid and normal usage, a professionally cleaned tank shouldn't show significant algae regrowth before its next scheduled service. Rapid regrowth usually points to a lid or seal issue that needs separate attention.
Don't wait for the water to look wrong
By the time contamination is visible or noticeable in taste, it has usually been developing for weeks. Routine cleaning on a fixed schedule prevents the problem entirely rather than reacting to it. Green Horizon provides licensed water tank cleaning and disinfection across the UAE — see our water tank cleaning service or book an inspection.