Loft Tanks

Loft tanks are designed as part of a gravity-fed cold water distribution system and are normally located in the loft or roof space. The water stored inside the loft tank feeds the taps and any other water outlets in the property. The higher the tank, the greater the amount of water pressure as a result if a cold water tank is located on the same level as the taps, there is not normally enough water pressure. A cold water loft tank can also supply water to a hot
water tank below.

Modern loft tanks are normally constructed from polyethylene plastic for strength and stability. Tanks are available in a wide range of sizes and are suitable for all types of properties, ranging from small houses to large commercial properties. A small loft tank would have around an 18 litre capacity, whereas a larger tank can be 200 liters
upwards.

Older properties occasionally still have galvanised steel loft tanks. However, these can be susceptible to corrosion and should be carefully maintained to prevent contamination of the cold water supply. Once the tank has begun to show signs of corrosion, it is possible it will soon start leaking. In order to prevent further damage, the tank should
either be repaired or replaced. If the tank is badly corroded, it is usually safer and more economical to replace it with a polyethylene plastic loft tank, as these are practically corrosion free.

Loft tanks need to be carefully maintained to ensure that the cold water contained within remains drinkable and any new tank installation should adhere to water regulatory Bylaws. Water should be well ventilated to keep it fresh. All connectors and valves should be designed to prevent light and insects entering the water supply, which would cause contamination. The overflow pipe should also be screened to prevent insects reaching the water. A reinforcement plate should be fitted to the tank wall around the float valve and the tank will also need an insulation jacket to prevent the water supply freezing over the winter months.

If the loft space has further insulation added at any point, it is important that the insulation jacket on the loft tank is checked because the loft space will get colder as a result of further loft insulation. The floor beneath the loft tank does not need to be insulated, but the recommended thickness of insulation around the tank and pipes is at least 50mm. All water pipes and overflow pipes from the loft tank need to be insulated and the two basic options are
mineral wool mat and pre-formed molded insulation foam.