Rainwater Harvesting Using Permeable Pavers

A rainwater harvesting system is a system of storing or saving rainwater to be used at a later time for practical purposes such as landscape irrigation. There are many types of rainwater harvesting systems such as cisterns or other storage roof-water runoff collection but no other system can accumulate more water than permeable pavers.

The idea is that you collect rainwater from your roof and other hard surfaces and you direct that water to a storage container. Many times the size of container is way too big to be practical. It just takes up too much real estate and its ugly, like ones shown here.

Building a storage system under a paver driveway is a good solution. There are several component parts to putting a system like this together.

The first is the storage tanks, system or vaults to be used. A very effective one is plastic box like the one shown here. This box can hold 32 gallons of water and can withstand a load of up to 4,800 pounds.

Next is to dig a hole to contain the plastic boxes like this.

Put a rubber liner in the hole and fill it up with the plastic blocks.

Once that is done the blocks are covered with a geotextile material with is a strong fabric that will help support the loads that will be placed over the top.

We are going to install permeable pavers as our surface and large gravel between the pavers and the plastic boxes. The greater the distance between the pavers and the box the more load it will be able to support. For this system 18 inches of gravel is needed.

Once that is installed, a 2 inch layer of pea gravel is used as bedding sand and the pavers are placed on top.

A permeable paver has wide gaps to allow the surface water to pass through and into the storage container. In addition to the direct rainwater that falls on the paving stone water can be harvested from nearby hard surfaces and roofs.

How Much Rainwater Harvesting Can Permeable Pavers Hold?

You can harvest 623 gallons of water for every 1000 square feet of harvesting area for each 1 inch of rain that falls.

A typical landscape water requirement will vary widely from region to region but as an example a medium use area in Southern California will need any where between 900 gallon to 1200 gallons for each 1000 square feet of landscape area.

Obviously the ideal situation would be when the rainfall matches ones watering needs.

A pump is used to get the water from your under ground storage to your landscape area.

Once the project is complete the paving area is 100% usable and there are no telltale signs of an ugly storage tank.