The tank is the one thing in a house nobody looks at and everybody uses. Because it is sealed, the first signal usually arrives through taste or smell, and that is a late signal, not an early one.
The interval, and when it stops applying
Twice a year is a reasonable baseline for a domestic tank in Jeddah. The baseline fails in three cases: a tank exposed to direct sun, a tank in a building with repeated supply interruptions, and a tank in a new building that has never been cleaned since construction. In those, the interval is shorter.
In a new building it pays to leave the tank until every dust-producing task on site is finished. That is the same sequencing that post-construction cleaning rests on: nothing starts until the trades have actually left.
The reason is that the interval is not really a number. It is the product of three things: how warm the water gets inside the tank, how much gets in from outside, and how long the water sits still. A family that travels for a month in summer comes home to water that has been standing at high temperature, which is the worst case there is, even if the last clean was recent. That is why we schedule a tank cleaning and disinfection visit around the condition of the tank and the building, not around the calendar alone.
The signs that come before taste
- Sediment in tap aerators: gritty particles or an earthy colour when you unscrew one.
- A shower head blocking repeatedly: uneven spray from some holes and not others.
- Cloudy water after an interruption: the interruption stirs the base, so whatever settled there resurfaces.
- A green tint on the inside wall: visible with a torch through the hatch, and it means light is getting in somewhere.
- A lid that does not seal: if the cover is cracked or propped open, the question is not when but now.
These do not have to appear together. One of them clearly present, particularly grit in the aerators, is enough reason to lift the lid and look at the base with a torch before deciding anything.
The scale that builds up on the outside of taps and shower heads is cleaning work rather than tank work. It needs a product left on it long enough to break the deposit down, not repeated scrubbing, and where that sits in a household schedule is covered in routine cleaning versus deep cleaning.
What actually builds up in there
What settles inside a tank is not one substance, and the difference is why one method does not remove all of it:
- Mineral sediment: fine sand and dissolved salts that drop out under gravity and compact over time into a layer that has to be scraped, not rinsed.
- Biofilm: a thin slippery layer bonded to the walls, barely visible but obvious to the touch, and the reason water goes off again after every refill if it is left in place.
- Algae: they cannot grow without light, so finding them points straight at a broken lid, a translucent wall or an open hatch.
- Foreign matter: leaves, insects and dust, all of which prove there is an opening that needs closing before anything else is done.
Roof and ground tanks are not the same
A ground tank is larger, cooler and less exposed to sunlight, so algae are less of a problem, but dust and insects reach it more easily because it sits at ground level. A roof tank is the reverse: protected from the ground, exposed to heat. They are inspected against different criteria, and cleaning one does not cover the other.
In practice a ground tank is judged on its openings: how well the lid seats, the state of the seal where pipes enter, and any crack in the concrete that could let water in from outside. A roof tank is judged on heat and light: the colour of the inner wall, whether it has shade or insulation above it, and how much water sits still at the base for days on end. In a building that runs both, cleaning only the roof tank means the ground tank will recontaminate it within days.
Common mistakes when people do it themselves
- Draining and refilling straight away: running water does not lift the layer bonded to the wall. Hand scraping does.
- Pouring disinfectant into a full tank: the concentration becomes anybody's guess, and it meets sediment rather than a clean wall.
- Scrubbing without rinsing enough: leftover cleaner leaves a taste that lasts for days and gets mistaken for the contamination itself.
- Climbing into a sealed tank without ventilation: a closed space can hold air that is low in oxygen, and going in alone is a real hazard rather than a theoretical one.
What to sort out before the visit
- Find the pump switch and turn it off, so the pump is not left running against an empty tank.
- Draw the level down beforehand if you can, since a partly emptied tank shortens the job.
- Keep some water aside for use during the work, because the supply will be off for a while.
- Point out any damp patch you have noticed around the tank. It usually marks a crack that only shows once the tank is empty.
The first hours after a clean
Once the tank is refilled, open a tap far from it and let it run for a minute or two so whatever is left in the pipework clears. Then check the colour and the taste. Slight cloudiness in the first few minutes is expected, because refilling disturbs the base again. If it is still cloudy an hour later, or a strong smell persists, that is worth raising rather than waiting out.
Why sediment sometimes returns fast
If a tank is cleaned and sediment reappears within weeks, the cause is usually not the cleaning but what surrounds it: a lid that does not seal, a vent with no mesh, or old feed pipework delivering what has collected inside it. Cleaning the tank alone in that case treats the symptom.
A simple test separates the two. Fill one glass from a tap near the tank and another from the furthest tap in the house, stand both on a level surface and compare them an hour later. If the far glass has more settled matter in it, the problem is in the pipework rather than the tank, and cleaning the tank again will not end it.
How we do it
We drain the tank, scrub the walls and base by hand, then disinfect and rinse until the water runs clear. Before sealing it we check the lid and the vent and tell you if either needs repair, even when that is not part of the agreed work.
We also hold off refilling until you have seen the base yourself, because once the tank is full there is no way to judge the work.
Before handing the work to anyone, the questions that come first are the same here as for any other service: who turns up, what is excluded, and what happens if you are not satisfied. They are collected in what to ask before booking a cleaning company.
Read what our water tank cleaning covers and what a visit includes, or get in touch for a price.