Harvest the Rain

1600 Gallon (6000 Liter) IBC rainwater storage

Rotterdam, Netherlands, 2024 - Harvest the Rain

Before

This rainwater storage project was part of a full schoolyard transformation with Moestuinman, a collective I am part of that is dedicated to transforming concrete schoolyards into adventurous playgrounds. The full playground was similar to what we see at almost all tradition Dutch schoolyards; completely concrete, covered with 30×30 tiles (1 foot x 1 foot). To learn more about Moestuinman and how we build green schoolyards, go to our website: Moestuinman, which is dedicated to just that! In this project description I will only focus on the stacked IBC tote rainwater harvesting structure. 

Plan

The municipality of Rotterdam is trying to motivate it’s citizens to harvest as much rainwater as they can. Part of this is a subsidy that will pay per square feet of ‘de-tiling’ and per cubic feet of water capture. Combined with the fact that this school was looking for additional funding to afford their Green Schoolyard, this was the reason we decided to go all-in.

We drew up the plans on harvesting with 1600 gallons (= 6000 Liters) in IBC rainwater storage, a natural wadi with a water capacity of well over 1100 cubic feet (= 32m3), and 3 separate rainpillars of 275 gallons (1000L) each.

The IBC rainwater system was the most complicated project. IBC totes are plastic containers of 275 gallons (1000L) that are normally used to save or transport fluids; from oil to breaker fluids and from drinking water to liquid food products. There are plenty of second hand cleaned IBC totes available everywhere and they can be a cheap way to store lots of water and reuse materials. 

IBC rainwater storage
Right after the build
The IBC system's overflow is connected to a wadi
IBC climbing vines
The IBC totes with climbing vines to eventually cover them

Build

The build was executed together with Waterleider, a local water harvesting expert. In the image gallery below the full working of the IBC water harvesting system is illustrated (in Dutch). 2 of the downspouts of the schoolbuilding that would otherwise be drained into the sewer system form the combined input for the stacked IBC system. The top 3 and the bottom 3 are ‘communicating’ barrels, meaning that they will fill up like they are one big tank.

Observation also remains crucial in bigger builds like these. For example, we noticed that the infiltration speed of water in the wadi was slower in. practice than what we initially thought and experimented with. Because of that, the wadi filled up quicker than we anticipated with both the rain falling directly in and around it, plus the overflow from the IBC rainwater system. Therefore we decided to later slightly alter the system so that the overflow could be directed either to the wadi or back to the sewer. 

Step by step working model (in dutch)

More questions?

If you want to know more about the process of desiging and building this system, or if you’re keen to brainstorm ideas for your outdoor area, just drop me a message or give me a call!