I need the details about underground water tank

details explanation of underground tank

Underground water storage tanks are used for underground storage of potable drinking water, wastewater, & rainwater collection. So whether you call it a water tank or water cistern, as long as you are storing water underground these are the storage tanks for you. The ribbed design of water cistern tanks makes it capable of being buried underground, supporting the surrounding soil. Driving over or placing a sidewalk over a buried water cistern tank is not permitted and will void the warranty. Plastic underground water tanks (cistern water tanks) is a great alternative to concrete cisterns.
Commonly Asked Questions on Underground Water Storage Tanks (Water Cisterns)

Can I install a underground water storage tank (water cistern) under a driveway.
No, installing the water tank (cistern tank) under a driveway is not permitted and will void the warranty. Do not locate tanks beneath driveways or in the pathway of heavy or vehicular traffic areas.
Is there a sand/gravel mixture recommended for bedding/backfill?
Yes, the sand/gravel mixture, commonly called “pea gravel” mixture is recommended.
Why is it recommended to fill the tank with water as the soil is being backfilled while burying the tank (cistern).
Filling the tank (cistern) with water while backfilling equalizes the pressure between the outside and the inside of the tank thus minimizing any possible distortion or movement of the tank (cistern). Underground tanks (cisterns), with the exception of those less than 550 gallons, should remain at least one fourth full at all times.
Can I use a below ground water tank (cistern) above ground?
Underground water storage tanks (underground water cisterns) are designed for below ground use only. Using the tanks above ground can result in deformation of the tank. It is far more cost-effective to utilize an above ground storage tank that is specifically designed for above ground use and applications.
Can underground water tanks (cistern tanks) store fresh potable drinking water?
Yes, made from FDA approved virgin polyethylene plastic resins, safe potable drinking water may be store in underground cisterns (tanks).
Can hot water be store in underground water storage tanks (underground water cisterns)?
Do not subject the tank to water temperature higher than 100 deg F, polyethylene storage tanks have a maximum storage temperature of 120 deg F. Contents with a temperature in excess of 120 def F, even for a short period of time, can weaken the tank’s structural integrity and make it susceptible to deformation and failure.
How do you access a underground water tanks (underground water cistern)?
Each below ground water storage tank (cistern tank) comes equipped with a manhole access hatch. In addition, risers can be added to the top of the tank providing ground level access. Without a riser you would need to dig up the soil above the manway to gain access.
Can fittings be installed?
Yes, fittings can be installed. Underground cisterns (water tanks) are not preplumbed. Bulkhead fittings or schedule 40 pipe are commonly installed.
Can they be connected to each other?
Yes, underground cisterns (water tanks) can be connected to one another. This is usually done with an added bulkhead fitting at the bottom of each tank.