Saving is the key word for anyone who builds or renovates. With a rainwater harvesting system, you save on your water bill by using rainwater for the toilet, washing machine, garden, etc. But how much does such an installation cost? We asked Philippe Courcelle, advisor at the water management company GEP Watermanagement in Harelbeke. Prices mentioned are excluding VAT.
The Rainwater Tank
What size should your rainwater tank be?
“According to regulations, you should calculate 50 liters per square meter of roof surface. For a 5,000-liter concrete tank (the mandatory minimum volume), the average cost is 772 euros. For a plastic tank, the average cost is 1,650 euros,” explains Philippe Courcelle.
The maximum authorized volume is 10,000 liters. A 10 m³ concrete tank costs around 1,120 euros and 2,360 euros if it’s made of plastic. Prices are excluding VAT and transport, but include leveling and the lid. You calculate the tank size based on 50 liters per square meter of roof.
“The choice of pump depends on the type of house, the location of the tank relative to the house, and your personal preferences,” says Philippe Courcelle. On average, a self-priming pump costs 530 euros, while a submersible pump inside the tank costs around 770 euros.
“The greater the distance and the more connected appliances there are—meaning higher needs—the higher the cost will be. Do you want an automatic refill system from the mains in case of low rainwater levels? Then expect to pay an additional 280 euros for an auxiliary pump system.”
The Filter
“In principle, a rainwater filter is the most important part of the system to prevent leaves and debris from reaching the bottom of the tank. This filter costs between 250 and 350 euros.”
“We always work with a floating suction hose costing 90 euros when using self-priming pumps. With submersible pumps, the floating suction is included in the price. A fine filter costs around 180 euros and captures the last particles present in the water.”
The Switching System
“Do you want an automatic switching system to mains water when the rainwater level is low? This system doesn’t refill the main tank with mains water but instead uses a small internal tank in the house for daily consumption,” adds Philippe Courcelle. “This system costs around 1,800 euros.”
“Again, the pump choice depends on the type of house, tank location, and your own preferences.” To activate the rainwater recovery system, it must be approved by the water supplier.
Installation Costs
The installation cost of a rainwater harvesting system is hard to estimate, as it depends on your situation. Whether it’s a new build or a renovation… Whether the area is easily accessible… Whether excavation work is needed… In renovation cases, the cost is often higher because the installation may require replacing certain pipes, which involves more demolition. Material costs (like pipes) are relatively low.
The Mandatory Certificate
Before the system can be put into use, the water supplier must verify it. The internal installation check ensures that the drinking water quality isn’t affected by the sanitary system in the house. These systems must be strictly separated. The price for this inspection depends on your municipality and supplier and averages around 130 euros.
Maintenance Costs
“In principle, rainwater recovery systems require little maintenance, so costs remain low. You simply need to remove settled sludge from the tank bottom and clean the filter 3 to 4 times a year, especially in autumn and spring.”
In the end, for a rainwater system with a concrete tank, expect to pay between 2,000 and 4,650 euros. For a plastic tank, the cost ranges between 2,900 and 6,000 euros. Don’t forget to add VAT, transport, and installation costs to the total.
Finally, visit our services page to see how Ateliers Thomquin can help you!
Sources: LIVIOS EDITORIAL TEAM, 04-06-20
