Turn your rainwater tank
into a revenue stream
Register your residential rainwater harvesting installation. Earn a 60% revenue share each time your verified water credits sell to corporate buyers. Free registration, satellite-verified.
60%
Revenue share to asset owners
$1.25
Per Verified Water Credit
85%
Effective collection after 15% integrity margin
1 m³
= 1 Verified Water Credit
Free & quick
Registration takes 5 minutes. There are no fees, no equipment to buy, and no commitment required.
Independent verification
We verify your installation using satellite imagery — no site visits or paperwork on your end.
Turn rain into credits
The rain you already collect generates Verified Water Credits you can sell to corporate buyers or count as a verified contribution toward your own household water use.
What is a Verified Water Credit?
One Verified Water Credit (VWC) equals one cubic metre — 1,000 litres — of verified water saving. Corporate buyers purchase VWCs at $1.25 each to account for their water footprint in line with CDP and SBTi reporting frameworks.
As an installation owner, you earn a 60% revenue share each time your verified credits sell. MarillionEx retains 40% to cover verification, administration, and platform costs.
How it works
Register your tank
Tell us about your roof catchment area, tank size, and upload photos. Free registration, takes 5 minutes.
Satellite verification
Our team verifies your installation using satellite imagery. You'll receive an email when verified (typically 5–10 business days).
Earn verified credits
Once active, your installation earns Verified Water Credits (VWCs) monthly based on your catchment size and local rainfall.
Receive your share
Corporate buyers purchase VWCs for their sustainability reporting. You receive a 60% revenue share each time your credits sell.
Methodology
Science-based calculation engine
We calculate your annual water saving using roof catchment area, local 10-year average rainfall (Open-Meteo historical archive), roof runoff coefficients, and a monthly tank-cap model that accounts for storage overflow in high-rainfall months.
- Monthly rainfall modelling — not just annual averages
- Tank overflow losses realistically applied
- 15% integrity margin for measurement uncertainty
- Satellite verification — independent of your submission
Example — Cape Town 120 m² roof, 5,000 L tank, 4 people
1 VWC = 1 m³ = 1,000 litres. Credits generated scale with roof size and local rainfall.
How it fits together
From your roof to a verified credit
Harvest
Rainwater harvesting is one of the oldest and most widespread water-saving practices in the world. If you collect and use rainwater, you're already reducing demand on stressed supplies.
Register & verify
Register your system in minutes. We verify it independently — including satellite imagery — and assess it against our Diamond Standard methodology.
Earn or contribute
Once verified and operating, the water you save can generate Verified Water Credits. Sell them to corporate buyers and earn a 60% revenue share, or retire them yourself as a verified contribution.
Not every system qualifies — eligibility depends on independent verification and additionality assessment.
Ready to register?
Free registration. 5 minutes. Start contributing to global water stewardship and earn your share.
Register my installation