There are many different reasons why you might need to have a water tank at your property. One of the most common is to have somewhere to store water that has been collected from the rain, giving you an eco-friendly way to utilise natural resources. Rainwater harvesting systems usually comprise a drainage system alongside a sizable tank to keep the harvested rainwater in until it is used in the property.
Houses use high quantities of water every day for everything from washing clothes to toilet flushing, showering, to pet cleaning. This means that the tanks that you potentially need will need to be pretty large. Water tanks can come in a range of sizes, as well as tanks specifically made for storing drinking water, horizontal water tanks, and horizontal static water tanks. These tanks are all generally stored above the ground. It is also possible, however, to store water tanks (including rainwater harvesting system tanks) under the ground.
Underground Water Tanks
One of the main problems with having a water tank above the ground is that it can take up a fair amount of room. This may not be a problem if you have a large outdoor space, but for many people, it can be rather imposing on their garden. Fortunately, a specially designed underground water tank can be the solution.
Being underground there are, of course, extra pressures put onto the tank that would not be there if it was to be kept above the ground – the weight of the earth around it, for example. Sizes can range from a small 900L underground water tank to a large 10,000L underground water tank.
Below ground water tanks are normally ribbed to give extra strength to the tank, enabling it to withstand the extra pressure that is put on it as a result of being underground.
Underground water storage tanks will normally be made of polyethylene – a strong and durable plastic that is robust enough to keep the stored water safe from leaks and other damage. They should be resistant to cold temperatures and UV rays.
Installing an Underground Water Tank
The process of installing an underground water tank is a fairly simple one as long as you have the right equipment.
The first step is to check the technical advice that has been issued by the government’s Environment Agency. It is probable that in the UK you will need to have planning permission to install a new underground water tank. You may also need to do a risk assessment.
It is recommended that the work is carried out by an expert to avoid any potential problems. The following installation instructions are a guide and the manufacturers installation instructions must always be followed. They will first excavate a pit where you wish to place your underground water tank. The pit will be slightly larger than the tank itself.
A level base should then be added to the bottom of the pit. This must be level in order for the tank to work properly and safely. It is recommended that pea gravel is used to create this, but flowable and compactable sand can also be used. The tank is then lowered into the pit, being rolled onto the gravel allowing itself to bed.
The connections are then made, linking the tank up with the house plumbing system and the water source.
Finally, layers of the backfill should be added to the pit, surrounding the tank evenly until it is completely filled – including underneath the pipes.
