Inline Rainwater recovery filter

This system is very basic. I will harvest water off a +150sqm roof and will be exclusively used for watering the garden and filling your pool. It does not contain any pressurized pump.

Key components:

  1. One round 5000l rainwater tanks situated near or at the gutter down-pipes.

  2. Good solid hard surface/platform

  3. One 110mm down-pipes from the gutters

  4. One inline primary WISY RS110 rainwater filter. The filter will be mounted in the down-pipe from the gutter. The inline filter fits onto the 110mm down-pipe and effectively screen and harvest the rainwater. These inline primary rainwater filters screen out any organic material greater than 280 microns. It ensures that the rainwater tank is kept clean with minimal sludge buildup in the tank, thus improving the water quality and reducing the cleaning frequency of the tank (you would only have to clean the tank once every 5 years). The correct installation of the RS110 inline filter does not require the installation of an tank overflow. If the tank is full the water will simply bypass the filter and run in the down-pipe onto the ground.  

  5. Tank level gauge so you can see the water level in the tank

  6. Outlet valve with a hose fitting

 Positive aspects.

  • The building is harvesting rainwater.

  • For every 10 mm the building will harvest 1500l or rain

  • It is the cheapest form of a well designed rainwater system

  • 1-2 days installation

  • Can be a basic DIY project


Negative aspects

  • There is not pressurized pump system. Thus you need to connect a hose to the system and open the tap. As the water level in the tank drops so the flow-rate and pressure of  the water pressure will drop. The maximum pressure you can get form a system like this is when the tank is full and that is about 0.2 Bar.  

  • The question is why would you want to water your garden when is raining. You need the water when it is dry - so the tank will fill up stay full in the raining season and only get used in the winter. Once it is empty you have to revert to municipal water gain until the rain comes, thus your comparative saving on reduced water consumption is small and limited to the two tanks volumes in the system.

  • Volume and value of water saving is limited to the amount of non pressurized water used. We estimated it in a basic household simulation to be about 40 000l per year.


Estimated on site installed cost ( Please note that these are estimates and can be used as guidelines only)


One 5000 tanks - R5400

Two RS110 Rainwater filters - R1900

PVC Down-pipe R250

Tank Base with R2500

Basic tank gauge - R500

Valve, brackets,  and accessories R800

Installation cost R3500

Total R 14850