Skip to Content

Rainsava Gravity

A low-energy underground rainwater harvesting system for homes with a suitable loft or high-level header tank.


Collect, filter and store rainwater underground, then pump it to a header tank for gravity-fed supply to toilets, washing machines and garden use, with mains water back-up when needed.





 How the system works

Key Benefits

Low-energy gravity supply

Rainwater is pumped to a header tank, then supplied by gravity.

 Reduced pump cycling

 The pump runs less often, helping reduce wear and noise.


Reliable header tank storage

A high-level tank keeps rainwater ready for toilets, washing machines and garden use.

Mains water back-up

Automatic top-up helps maintain supply when rainwater levels are low.

 What's Included?

  •  Underground storage tank with clamed inlet and anti-backflow valve
  • Wisy Vortex filter with 0.28 mm stainless mesh
  • Automatic submersible pump
  • WISY mains water top-up kit
  • 25m of 32mm MDPE pipe
Rainsava Gravity 

Pumped rainwater supply to a header tank for simple gravity-fed use. Reliable and economical.

Rainsava Eco-Pro 

Advanced Monitoring and smart controls for maximum efficiency and insight.

Rainsava Classic 

Simple reliable and automatic. Built in pressure switch pump provides hassle-free operation.