Problems retrofitting rainwater harvesting systems in existing homes

There are 4 main problems of retrofitting a rainwater harvesting system into your existing home. The price, disruption causes, changes to pipes and drains.

close up rainwater harvesting system

On some occasions you may want to retrofit a rainwater harvesting system in your home. Although rainwater harvesting systems can be installed into most buildings it is best suited to newer properties.

There are certain aspects you will need to consider before you install a rainwater harvesting system into your existing property.


Disadvantages of retrofitting a rainwater harvesting system 

  • Cost
  • Disruptive aspects
  • Changes to pipework and plumbing
  • Issues with the drainage system



The price of retrofitting a rainwater harvesting system into an existing home can be high.  This is because the installation is disruptive, and more maintenance is needed over time (than in a new building).

The Disruptive Aspects:

Rainwater harvesting systems often require an underground storage tank.  This is to store the water until it is needed.  However, it is expensive to install an underground storage tank, and this will be disruptive.

You may even need to re-route some services in order to accommodate the installation process.


Changes to Pipework and Plumbing:

It is likely a certain amount of changers will be needed with the pipework when fitting a tank and drainage system. There would also be substantial changes to the plumbing system when fitting a rainwater harvesting system into an existing home.

Issues with the Drainage System:

The drainage system should only be carrying the rainwater from the collection surface, on the roof and transporting this to the storage tank. The system could require changes if you decide to carry grey water (water from baths and basins). This is more common in older homes.

Overcoming these Issues:

In order to overcome the issue of the installing the storage tank underground, which can be expensive it is possible to have the tank above ground level. The tank can then either be located inside the property or just outside. This can only be achieved, if it is possible to direct some of the existing rainwater downpipes to the storage tank.

It is recommended that all of these aspects should be taken into consideration prior to the retrofitting a rainwater harvesting system into an existing home.


Image Sourced: Chiot’s Run                                                             

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