Converting a Swimming Pool to a Rainwater Tank

Spending more time tending to your pool than swimming in it? Tired of toxic chemicals and endless maintenance? Now you’ve got options.  Rainwater Harvesting Systems, Inc. (Australia) explains the process of converting a swimming pool to a rainwater tank.

swimming pool to rain water tank conversion

Now more than ever, smart people are thinking sustainably about the resources they use and how much money goes “down the drain” every month.   If you’re the proud owner of a swimming pool, then you know they are one of the biggest drains of time, energy and money in the maintenance of your home and landscape.  Why not make your swimming pool work for you?

Rainwater harvesting technology has come a long way in the past 5 years.  Using a simple but robust technology, your swimming pool can be utilized as an underground rainwater harvesting cistern or reservoir.  Water collected from your rooftop is filtered, stored and pumped up on demand to satisfy your water demands.  The top of the tank is brought to ground level and can be covered with grass, stone work, a wooden deck, or any other landscape material you’d like.

Frequently Asked Questions

How much does a pool demolition cost?

Perhaps you’ve simply stopped using your pool because the kids grew up, the endless maintenance has gotten the best of you, or the cost has become too much to justify.   Most people facing these circumstances initially consider the possibility of having a pool demolished, backfilled with soil and made into a lawn.  The cost to have a pool “demo’d” can be significant.  Hiring a general contractor to break and remove the coping, remove the filters systems, cap the electrical lines, backfill the pool and bring up to grade will cost somewhere in the neighborhood of $3,000-$10,000 for a family size pool, depending on site access, size of the pool, cover material plus other considerations.

Can all swimming pools be converted to rainwater cistern?

The short answer is yes.  Even if your pool is oddly shaped, has different depths or doesn’t currently hold water, we can almost certainly find a way to convert your pool to a rainwater cistern.

What can I use the water for?

Water collected from your roof can be used for many different purposes.  The most common are landscape irrigation, wash water and water feature refill.  In some circumstances, water from an underground rain water tank can be used for indoor purposes.  However, the materials used to create the internal structure of the rainwater tank are often made from recycled plastics, which is good for the environment, but provides water for non-potable uses only.  If you require drinking-water quality from your rainwater tank, we have a solution for that too which involves using NSF certified drinking water components and filtration systems.

How much water can I collect/save?

There are two values used to calculate how much water you can potentially save annually by collecting and recycling rainwater.

  1. Collection Area- The total square feet of your roof “footprint” (also referred to as your “total slab”) you will collect from..  A common household may range from 1,500 to 3,500 square feet.
  2. Annual Rainfall- How many inches of rain will fall on your roof on average during a year?  To find this, Google “annual rainfall (your city)”.
Collection potential (P) = Collection area (A) x Annual rainfall (R) x Conversion factor (C)
Example: P = 2,000 sq. ft. (A) x 40 inches of rainfall (R) x .62 (C)
P = 49,600 gallons per year.
By taking other factors into consideration such as the size of the water storage tank, local rainfall patterns in your area, and the frequency with which you use the water in the tank, we can design a system that consistently provides clean water for your needs.

How does the conversion work?

Converting a swimming pool to a rainwater tank involves 6 basic steps.

  1. Remove unneeded equipment and materials from the site such as coping, pool filter systems, diving boards, electrical lines, etc.
  2. Prepare the pool.  This involves checking for water-tightness, leveling the bottom, adding sealants or liners, etc.
  3. Build the tank.  We use an underground structural retention system that supports the weight of the backfill material while still providing > 90% holding capacity.
  4. Backfill and grade.  We add aggregate materials, filter fabric and select backfill to fill in around the tank and bring the site up to grade.
  5. Direct clean rainwater to tank.  Underground pipes connected to your downspouts funnel water to the tank.  Inline, self-cleaning filters remove all manner of debris from the water so only clean rainwater enters the tank.
  6. Add pump, controls and other equipment.  At a minimum, an underground rainwater requires a submersible pump, post-tank filter and a level indicator.  Beyond that, many other accessories can be designed into the tank, such as an automated make-up water feature, advanced filtration, aeration systems and much more.

How much does it cost to convert a swimming pool to a rainwater tank?

A major consideration for converting a swimming pool to a rainwater tank is the cost.  First, ask yourself these three questions to determine the amount of time, money and effort you are already investing in pool maintenance.

  1. What is my annual expenditure for pool chemicals, cleanings and filter replacements?
  2. How much have I spent in the past 3 years on replacement parts, such as pumps, vacuum systems, etc.?
  3. How much time do I spend thinking about and performing pool maintenance when I could be doing something else?
If you start to add up all of the “investments” you’re currently making into your pool, chances are you’re already spending thousands of dollars per year.  Upfront costs to make a conversion aren’t cheap, but neither is having a pool demo’d, nor is your annual maintenance.  So the question becomes- what is the best long term solution for the endless maintenance and expense of a pool?  Furthermore, how can I use the existing pool to my advantage to collect resources for me, even when I’m sleeping?
On average, creating an underground rainwater harvesting storage system, along with the necessary collection pipes, filters, pumps and controls will cost in the neighborhood of $3.00 per gallon installed.  An average size pool holds around 20,000 gallons.   Keep in mind that the entire pool does not necessarily need to be filled with the collection tank.  It is easy for us to build the tank in half of the pool and bring the rest to grade using gravel or other backfill materials.
Converting a swimming pool to a rainwater tank is a significant investment, but a smart investment indeed.  You will immediately eliminate annual pool maintenance expenses and your system will provide free water to you for decades to come.  In an era of dwindling water resources and ever-tightening water restrictions, your own personal water source may be one of the best investments you can make right now.

Source: Rainwater Harvesting Systems, Inc. (Australia)

Converting a swimming pool to a rain water tank, especially if it is never used for its original intended purpose, is certainly a wise decision in many parts of the world, including South Africa where a water crisis is looming.  Should you wish to retain your swimming pool, there are many types and and sizes of rain water tanks to choose from.  It is important to choose high quality water tanks from trusted brands such as JoJo Tanks.  A wide range of water tanks, rainwater tanks, tank stands, septic tanks and other high quality products are manufactured by JoJo Tanks in South Africa.  Click on the links below to find your ideal JoJo Tanks product.

JoJo Tanks South Africa offer a wide range of plastic water tanks and chemical tanks to suit every household, business or agricultural need, including silo tanks and silo tank stands.  See JoJo Tanks VERTICAL TANKS, HORIZONTAL TANKS (transporter tanks), STEEL TANK STANDS and OTHER JOJO PRODUCTS. Also see JoJo Tanks’ NEW 6000 LITRE UNDERGROUND TANKS. Also see our FAQ and WATER TANK PRICES.

JoJo’s superior polyethylene plastic water tanks and steel water tank stands make JoJo Tanks the leaders in plastic water tank technology and the quality, affordability and guarantee on these water tanks make JoJo products the best choice in South Africa.  JoJo’s water tanks and chemical tanks come standard with a number of features that are often lacking on cheaper/inferior plastic tanks made by other companies in South Africa.

We are authorised JoJo Tanks dealers in South Africa and dispatch orders directly from JoJo Tank depots to save on transport costs. Full range of JoJo Tanks products and JoJo water tanks for sale.  CONTACT US for a quote on the right JoJo water tank or other JoJo product for you.  Special discounts are available on multiple orders of chemical tanks and water tanks and to our commercial and government customers.


(15000 litre and 20000 litre JoJo vertical water tanks also available on order)

Live in the USA and need rainwater harvesting equipment?  Click HERE!

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