Installing an underground potable water tank is an effective way to store drinking/cooking water on your property, especially if you do not live within the radius of official water supply lines. However, these water tanks must be cleaned, maintained and inspected regularly to ensure that the water remains healthy and safe for human consumption. This article discusses factors that can interfere with your water safety and how you can deal with them.

1. Leaks

Underground tanks can develop leaks or cracks due structural damage from earthquakes or tremors and other factors. Undetected, such cracks are likely to spread, causing major damage by the time they work their way to the top surface where they are easily noticeable. It isn't unheard of to have your underground tank collapsing because of widespread cracking and/or leaking.

Given its location, regular inspection is the only way to detect and repair leaks before they get out of hand — ensure that the tank is inspected every six months. In addition, call for inspection if you notice a drop in water pressure, presence of dirt in your tank water or unexplainable water loss. Schedule an inspection following any earth movements, like quakes, tremors and even landslides, to ensure that the tank did not sustain any damage.

2. Sludge

Sludge is formed as a result of accumulation of sediments, particles and organic materials that find their way into the tank. In time, the layer of sludge forms suitable ground for growth of harmful microorganisms which make your water unsafe. At your scheduled six-monthly inspection, the bottom of the tank should be checked for sludge and it should be cleaned out where present. For non-potable water, inspection every 2-3 years is recommended, but more regular inspection is required for potable water because of associated health risks.

Manual cleaning out can be dangerous and hence should be done by qualified inspection and service technicians. Alternatively, you can invest in a tank cleaning pump which vacuums out the water — though this is not a worthwhile investment unless you're using it frequently, e.g. if sludge builds up often.

The best way to control sludge is to install strainers and filters at the inflow point of the tank to keep as many sediments out of the tank as possible. In addition, having a self-cleaning system will ensure that all sediments are cleaned out on arrival so that sludge isn't allowed to form. These systems are available with water tank manufacturing and installation companies, so you can have them installed along with the tank.