The Financial Benefits of Rainwater Harvesting

How the financial benefits of rainwater harvesting can be calculated, and when you’ll start to see them.


If you’re tired of having to keep up with the rising costs of water, or if you can’t find any way to justify paying for what is essential to your survival, then rainwater harvesting might be for you. The decision to take this route might be based upon ethics, but the financial benefits of rainwater harvesting won’t make the decision any harder.

The variables

The financial benefits of rainwater harvesting will be different for each household. The efficiency of any one system will be dependent upon such things as:

  • The total water consumption of the household
  • The size of your family
  • The length of time that the tank remains empty or in drought (such as during warmer, dryer summer months)
  • The water rates in your local area
  • The size of your rainwater harvesting storage tank
  • The number of appliances which the rainwater will be used for apart from being used as drinking water

Let’s consider the average daily water use per person to be 110 litres. This can be broken down into activities such as:

  • Bathing or showering: 44 litres
  • Toilet flushing: 30 litres
  • Washing laundry: 17 litres
  • Washing dishes: 8 litres
  • Cleaning: 8 litres
  • Cooking and drinking: 3 litres

Swapping mains water for rainwater is a great way of making a significant saving in non-drinking water. It can supply up to 50% of the total household consumption in many cases. Harvested water will normally be used for things such as flushing the toilet, running the washing machine, cleaning, or watering the garden.

Payback Period

The time it takes to make back the money you will save by investing in a rainwater harvesting system will depend upon:

  • How much you pay for installation
  • Any subsidies available
  • How efficient the installation is
  • Water and waste-water treatment where treatment is needed

The payback period is likely to be shorter as time goes on. Strict new European environmental regulations such as the Water Framework Directive will impact upon the operational costs of water companies, therefore driving up their prices.

On top of higher operating costs, an ever-expanding population is putting more pressure on existing sewage, waste water treatment, and clean drinking water systems. Public authorities are having to invest more money in such systems, leading to greater increases to the cost of water.

Whilst the cost of fitting a harvesting tank may seem high, the financial benefits of rainwater harvesting are sure to make themselves clear in a very short time.

Image by Nishanth Jois

post your comment




One of the most effective ways to encourage wildlife into your garden is by introducing a pond. This guide will show you how to build a pond which your local wildlife will thank you for!

how to build a pond

Here's just a few useful and fun ways you can use the shells of pistachios and other nuts instead of throwing them away

pistachio shells

Find out how to keep your sugar intake low and avoid health problems such as joint inflammation and heart disease


Patagonia's unique approach to revealing information on their manufacturing process is something all aspiring green businesses could take a tip from.