Water Storage Tanks and Disinfection
A practical guide to storing potable water safely in buildings — why tanks are needed, how sealing, venting and turnover protect quality, and how disinfection and maintenance keep stored water fit to drink.
Most buildings cannot rely on the utility main alone to feed every floor at all times, so they store a reserve of potable water and re-pressurize it. That stored water buffers demand peaks and supply interruptions, but storage also introduces a risk: water that sits still, warms up or becomes contaminated can lose the quality it had when it arrived.
Protecting stored drinking water is therefore a core plumbing responsibility. It rests on a few principles working together — the right materials, a properly sealed and vented tank, enough turnover so water does not stagnate, and disinfection that keeps it safe. This lesson explains how a potable storage tank is designed and maintained to deliver clean water reliably.
How it works
Why storage is needed. A storage tank decouples the building’s demand from the utility supply. It lets pumps draw a steady, controlled flow rather than surging the main, provides a reserve during peak use or short interruptions, and gives a defined volume that pumps and boosters can be sized around.
Sealing and protection from contamination. A potable tank must be fully closed so that dust, insects, birds and surface water cannot enter. The lid is sealed; any opening — vent, overflow or inspection hatch — is screened and arranged to exclude contaminants. The tank is positioned and protected so that nothing non-potable can get in.
Vent, overflow and the air gap. A tank needs to breathe as its level rises and falls, so it has a screened vent. It also has an overflow to discharge safely if the inlet valve fails. Critically, the inlet is arranged with an air gap above the maximum water level so that, even under a fault, water from the tank can never be drawn back into the incoming main — a basic cross-connection safeguard.
Materials and turnover. Tank materials and linings must be approved as potable-safe so they do not taint the water or support growth. Just as important is turnover: the stored volume should be used and replenished often enough that water does not sit stagnant. Oversized tanks that turn over slowly can let temperature rise and disinfectant fade, so storage is sized to real demand, not simply made as large as possible.
Disinfection and maintenance. Potable water leaves the treatment works disinfected, and a measurable disinfectant residual helps keep it safe through storage and distribution. In the building, that is supported by good turnover, a clean sealed tank, and a routine of periodic inspection, cleaning and water-quality testing. Together these keep stored water fit to drink right up to the tap.
Main types
In the UAE
- In Abu Dhabi, ADDC supplies treated potable water, while standards for potable storage, materials and water quality are set primarily by the Department of Energy (DoE) alongside the Abu Dhabi Public Health Centre and the municipality.
- Storage tanks must use potable-safe materials and be sealed, screened and regularly cleaned and tested so the warm climate does not degrade stored water quality.
- Tank sizing balances reserve capacity against turnover: enough storage for demand and short interruptions, but not so much that water stagnates and warms before it is used.
How GPR applies this
GPR designs, supplies and installs potable water storage as part of its MEP scope in Abu Dhabi — correctly sized ground and roof tanks in potable-safe materials, with sealed lids, screened vents, level control, air-gapped inlets and overflow and wash-out arrangements. GPR coordinates storage with the booster pumps it sizes around it, and sets up the access and routine needed for periodic cleaning, disinfection and water-quality testing.
Frequently asked questions
Why do buildings store potable water instead of feeding straight from the main?
Storage buffers demand peaks and short supply interruptions and lets pumps draw a steady, controlled flow rather than surging the utility main — and it gives a defined volume to size pumps around.
How is stored drinking water kept clean?
By using potable-safe materials, fully sealing and screening the tank, keeping enough turnover so water does not stagnate, maintaining a disinfectant residual, and cleaning and testing the tank on a routine.
What is the air gap on a tank inlet for?
It is a physical gap above the maximum water level so that, even if something fails, water can never be siphoned back from the tank into the incoming main — preventing cross-contamination.
Why can a tank that is too large be a problem?
If storage is far bigger than demand, water turns over slowly, can warm up and lose its disinfectant residual, increasing the risk of quality problems. Tanks are sized to real demand.
How often should a potable tank be cleaned?
On a regular periodic schedule, with inspection and water-quality testing; the exact interval follows the building’s use and the applicable health-authority requirements.