How to Build a Water Storage Tank

Nathaniel Miller

Water tanks allow a homeowner to store a large amount of water in the event of a power outage, bad pump motor or dry spell in their well production.

Example of one type of cement water tank

Today, the majority of water storage tanks on the market are plastic; however, concrete storage tanks last longer, are customizable, and oftentimes cheaper in the long run. Building a concrete water storage tank will take less than a week and can cost as little as $1,500, from start to finish. Follow the steps below to build your own concrete water storage tank that will supply all of your water needs.


To ensure your concrete cures correctly, keep the walls wet for a week by spraying them down with water at the beginning and end of each day.


Always employ a friend when working on a project of this magnitude as there is a lot of heavy lifting involved.

  1. Begin by leveling off your build site. You want to make a perfectly level area that is slightly larger than your tank. This can be accomplished by hiring a backhoe service or doing lots of digging by hand.

  2. Build a set of forms for your initial floor pad (normally 10 feet by 10 feet) by building a square with lumber and plywood. Make sure there are no holes in the form, from which concrete could escape.

  3. Fill the pad form with gravel to a depth of approximately 8 inches. Now, pour your concrete on top of this "bed" to a depth of approximately 4 inches. Allow this pad to set up for a day before moving on to the next step.

  4. Build box forms from lumber that are 8 feet tall by 6 inches wide and as long as each side of your tank. Stake these into the ground, butting them up against your floor pad and making sure they are plumb, or perfectly vertical. Pour concrete into each form and tap the sides firmly to make sure the cement is distributed evenly throughout the form. Seat a sill plate (2-inch-by-4-inch board) along the length of the top of each wall, to later screw the roof into. Repeat this for each side of the storage tank.

  5. While the cement is still wet, drill a hole through the side of the tank, which you will use to route your plumbing. Insert the 1-inch PVC pipe to use as an outlet/inlet and allow the cement to set up around it.

  6. Allow the tank to set up for 48-72 hours and then seal the inside of your tank using Thoroseal or a similar cement sealer. This provides a waterproof seal that will keep you tank protected for years to come.

  7. Build a roof of your choosing (gable, barn, or lean to style) by screwing pre-made rafters into the sill plates on top of each wall, covering with plywood and laying down roofing material. You could also cap with a concrete slab poured much the same as your floor and then lifted onto the top of the walls. Hook up your inlet and outlet plumbing, turn the pumps on and you are good to go.