Flush with Rain

Freshwater sustainability for gulf island residents and homeowners means taking climate action – adapting high water use behaviour to much reduced levels for a water-wise future

This post is a quick summary of facts about non-potable rainwater storage systems for indoor uses like toilet flushing

More detail? Click here for the Guide

Why consider flushing with rain?

  • Flushing human waste is cited as the highest indoor daily water use in a typical home – on average one person flushes 5 times per day!
  • Installing dual flush toilets (4.3 L per flush, on average) can conserve flush water usage by 65%!
  • Flushing with rainwater will assist in conservation of groundwater and surface water (lakes, streams) for ecological and human potable uses.

Wondering about using rainwater to flush? What is involved?

Read on….it may be right for you!

Plumbing
  • Non-potable rainwater from onsite storage may be piped into the home for non-potable use in flushing toilets (according to the BC Plumbing Code).
  • Such systems must be designed, fabricated and installed in accordance with good engineering practice (CSA B128.1 Design and Installation of Non-potable water systems).
  • Non-potable water must meet applicable water quality standards as determined by local authorities.
Building
  • Inquire at the CRD Building Office about qualified professionals for this certification and once submitted, your system may qualify for a Building Permit which is required for legal operation (BC Building Code )
  • Additional uses for non-potable water in the home may be permitted when “systems are designed, fabricated and installed in accordance with good engineering practice”. For example, use of non-potable rainwater for cold water clothes washing (within a washing machine, not a sink faucet).
  • Treatment standards for such non-potable rainwater uses indoors should follow Health Canada guidelines as indicated in the Appendix to the BC Building Code (2018).
  • This non-potable water use in the home requires Dual-plumbing (https://en.wikipedia.org/wiki/Dual_piping) so that there is no possibility of contamination of your potable water supply with non-potable rainwater ( completely separate in its own pipes). It’s recommended to consult with a certified plumber early in the design of the system to ensure this will be feasible before you begin the engineered design process.

Do I require Islands Trust permits for onsite rain storage?

What steps do I take to authorize rainwater storage for toilet flushing? – See the Decision Tree – click here

A development permit may be required by Islands Trust to install onsite rainwater storage systems for both non-potable or potable uses based on the site plan and lot line setbacks. Consult with Islands Trust if you plan to install / build rainwater storage on your property.

References:

Design and Installation of Non-Potable Rainwater Systems CSA B128.1

Salt Spring Island Non-Potable Rainwater harvesting Best Practices Guidebook for more tips and tools in system design.

Salt Spring Island Non-Potable Rainwater Harvesting Best Practices Guidebook