How to Choose a Water Tank

Installed above or below ground?

When planning the installation of a rain water tank, it is important to consider where it can be located on your property. In many cases water tanks are installed above ground, especially when the water tank is being installed alongside an existing dwelling. However installing the water tank underground can be a good space saving solution.

water tanks

Water Tank materials – selection criteria

When determining the type of water tank to install, consider:

  • What ground surface preparation is required
  • Whether the vessel can be installed above or below ground
  • How easily the material is to repair
  • What manufacturer guarantee is available

An overview of types of water tanks available

Concrete water tanks

water tanks

An ideal in-ground solution. Feature load bearing tank lids, so they can be installed under garages or driveways.
Site Preparation : Compacted cracker dust or compacted sand, stabilised around the edge
In Ground : Yes
Guarantee : Ask your supplier for a written one prior to purchase
Repairable : Difficult to repair cracks if they occur. Consult the manufacturer

Metal/Steel water tanks

water tank


Extremely strong water tanks with polyethylene tank linings to prevent corrosion and ensure water quality.
Site Preparation : A concrete base is required or an approved tank stand
In Ground : No
Guarantee : Ask your supplier for a written guarantee for both the material & the workmanship.
Repairable : Yes, seams can be resealed by the manufacturer.

Poly/Plastic water tanks

water tanks


Popular due to its lightweight material which makes for easy site preparation and installation. Poly water tanks are now the most common for household use and come in a variety of shapes, sizes and colours.
Site Preparation : A base of cracker dust or sand
In Ground : Yes, consult the manufacturer
Guarantee : Ask for the manufacturers guarantee
Repairable : Yes, consult the manufacturer

Fibreglass water tanks

water tanks


Corrosion resistant and sturdy, fibreglass water tanks are a relatively expensive but long-lasting option.

Site Preparation : Compacted cracker dust or compacted cement stabilised sand or concrete pad
In Ground : Consult the manufacturer
Guarantee : Ask your supplier for a written one prior to purchase
Repairable : Yes, consult the manufacturer.

Bladders & other new innovations

New space saving bladders and modular storage systems have been developed in recent years. These water storage vessels provide wonderful solutions, particularly for urban areas.

water tank


Space saving option. An ideal for under house or under verandah water storage.
Site Preparation : Compacted cracker dust or compacted cement stabilised sand or concrete pad. The area must be clear of rocks, tiles and other debris. Smooth the ground, leaving a slight fall towards the outlet end of the Sac.
In Ground : Consult the manufacturer
Guarantee : Ask your supplier for a written one prior to purchase
Repairable : Yes, consult the manufacturer.

Choosing the size of your water tank

Factors to consider Things you need to consider when determining the size of your water tank or storage vessel include:
1. Rainfall – how much rainfall you get in your area,
2. Roof area – how large the catchment surface is,
3. Water usage – what you intend to use rainwater for, and how much you expect to use,
4. Site characteristics – how much space you have, and the location you intend to install the water tank or storage vessel.

Calculating the appropriate size

Use the following formula:
Roof Area  X  Annual Rainfall  =  Maximum Available for Capture

Then determine:
Most Days without Rain  X  Average Daily Water Use  = Storage Volume Required on Day One of a Dry Spell

If for example, the most days without rain was 40 days, and the average daily usage was 400L, the volume on hand on Day One of 40 days would have to be 16,000L.

It is very difficult to predict the required volume, because often a dry period will start when the water tank is not full. However, this method provides a guideline, and you can add a safety factor on top of this requirement.

When calculating how big the storage capacity should be, plan the water tank area so that extra storage can be added later if required.

Location for the water tank

It is important to consider the space you have available, whether the vessel is to be installed above or below ground, below the roof-line or above it (eg. on a sloping site), whether you will have one or more water tanks – connected or installed as separate systems, and what ground surface preparation is required.

Source: Excerpts from Rain Harvesting

Selection of a water tank must be considered carefully.  Aesthetics, shape, application and space available will influence the final choice.  Water Rhapsody consultants are trained to assess your requirements based on a number of factors (many are listed above) and will be able to calculate the appropriate size for you.  There are still many asbestos water tanks in use around South Africa and in the Lowveld.  If you currently use one of these water tanks for drinking water, you should consider replacing it with a water tank made from one of the materials mentioned above.  Asbestos fibres can cause serious illnesses, including cancer.  Water tanks are the core feature of a rain water harvesting system.  Once a rainrunner is fitted to your roof’s gutter, the water is channeled to a water tank.  The water tanks can be placed away from house and hidden from view, if necessary as these systems employ pumps to pressurize the water.  An Uninterrupted Pressurized Water Supply (UPWS) system is connected to your usual supply of water in case the rain water tank is depleted.

Water Rhapsody Mpumalanga is an authorzed JoJo Tanks dealer in South Africa.

We will try to beat any formal quotation on JoJo tanks in South Africa. Email your quotations to and let us see if we can offer you a better price.

Water Rhapsody Water Conservation Systems and Yes Solar Mpumalanga offer eco-friendly rainwater collection systems, rainwater tanks, grey water recycling, swimming pool backwash recycling, water-saving toilet flush mechanisms and high quality Solsquare solar water geysers.

Contact us for a FREE QUOTE on a solar water heater, rainwater harvesting system (see rainwater FAQ), gray water recycling system or water tank (we are authorized South African JoJo Water Tanks dealers and supply the full range of JoJo water tanks and JoJo tank stands).  Our water tank prices are hard to beat in the Mpumalanga & Limpopo Lowveld.

Water conservation and renewable energy such as solar energy are two issues that affect the global community; make a difference and start conserving water and switch to renewable energy today.  Another way of reducing your carbon footprint is to switch to green insurance, now available in South Africa.







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