Underground tank is a hidden solution of storing water as part of a booster set. Size of the tank is chosen based on the water usage of irrigation system and the filling flow.
Usually made from medium-density polyethylene, these tanks are durable, frostproof and maintenance-free.
Most of the time, the only access to any of the system components is via the manhole, although there might be many of them, like float switches, pump, inlets and outlets with equipments, filters, etc. Sometimes water distribution unit can also be found here. Hence it’s extremely important the manhole must be accessible for service purposes all the time.
Tanks themselves are maintenance-free. A tank can crack if its base has been sunk unevenly but this is a very rare situation. At the winter shut down, it worth to mark the water level and also check at the spring opening. If there is a level drop, it refers to a possible leak on the tank.