5 key things to know about rainwater harvesting systems

Water is a precious resource, and with the average family spending approximately 500 euros annually on tap water, it’s no surprise that many are turning to rainwater harvesting as a cost-effective solution. If you’re considering this eco-friendly approach, here are five crucial things you should know.

Underground rainwater storage

1. Setting up a Rainwater Tank

The first step in utilizing rainwater is collecting it. Most rainwater harvesting systems comprise gutters that channel water from the roof directly into a storage tank. However, it’s essential to note that roofs made of copper, lead, or aluminum are unsuitable for this purpose. These materials can dissolve in rainwater, posing health risks when consumed. Similarly, wooden roofs are not recommended as oils from the wood can discolor the water. Some experts also advise against using rainwater from flat roofs. It’s always best to consult with a roofing specialist to determine the suitability of your roof.

2. The Need for a Pump

To distribute the collected rainwater throughout your property, you’ll need a pump. Various models are available, including submersible ones. However, it’s advisable to install the pump in an easily accessible location, as pump-related issues are not uncommon. Regular maintenance can help prolong the pump’s lifespan and ensure efficient water distribution.

3. Filtering the Rainwater

Once collected, it’s vital to filter the rainwater to ensure its quality. You can install one or multiple filters downstream of the pump. Alternatively, a filter can be placed between the gutter and the rainwater tank. Several filter types are available in the market, so it’s essential to research and choose one that best fits your needs.

4. Maintaining the Storage Tank

Rainwater is typically stored in concrete tanks, which naturally neutralize acidic rain, slightly mineralizing the water in the process. It’s worth noting that plastic tanks don’t alter the water’s pH. Regardless of the tank material, regular cleaning is crucial. Over time, sediment can accumulate at the bottom, forming a layer of sludge that needs to be removed to maintain water quality.

5. Sizing and Cost Considerations

For an average family using rainwater for toilets, laundry, and an external tap, a 5,000-liter tank is usually sufficient. However, if you plan to use the rainwater for additional purposes like cleaning, gardening, or other household chores, it’s wise to invest in a larger tank.

The cost of setting up a rainwater harvesting system varies based on several factors, but you can expect an investment ranging between 3,500 to 4,000 euros. While this might seem like a significant upfront cost, the long-term savings on your water bill will ensure the system pays for itself over time.


Rainwater harvesting is not only an excellent way to save money but also a sustainable approach to conserving water. By understanding the intricacies of setting up and maintaining such a system, you can make an informed decision and contribute to a greener future.