Conserve Scarce Water – Rainwater Harvesting

Fresh Water on Your Islands

"Water, water everywhere, nor any drop to drink" - Samuel Taylor Coleridge, The Rime of the Ancient Mariner

Surrounded by saltwater, our island communities are at the whim of the weather, relying on annual rainfall for our fresh water needs.  With few freshwater lakes and wetlands, the Gulf Islands have limited spaces to store surface and groundwater.  We lose up to 80% of rainwater as runoff to the ocean.

Although we see rain in the winter, our Mediterranean-like weather is known for the hot, dry summers here where the islands can go for long spells without any rainfall.  Though great for attracting tourists and seasonal residents, the population swells the islands see each summer place extraordinary demands on our watersheds just as our water supplies are dwindling.  Fresh, drinkable water is a scarce resource in the islands.  We're already seeing some communities grappling with issues such as contaminated surface and groundwater, lack of water, and conflict over access to water.

Rainwater Harvesting

The biggest users of water on the islands are homes and tourist accommodations.  Rainwater harvesting is becoming more relevant to Gulf Island residents as problems with groundwater and surface water quality and quantity becomes ever more common and urgent.  Harvesting rainwater on your property enables you to lessen your reliance on community water supplies.  It also allows you to stockpile freshwater for dryer months, lessening your draw on other sources when our natural ecosystems need water the most. 

The average Gulf Island home can capture 91,000 to 105,000 litres of water a year with an average rainfall.  That's enough to provide about half the supply for a four-person water-saving household.  How much your system costs depends on its complexity, but a simple catchment system for an average house can usually be installed for between $2,500 and $5,000 with additional funding needed for a storage cistern.  Regular maintenance is crucial to the continued functioning of the system.

The Islands Trust Conservancy's Rainwater Harvesting Demonstration Site

In 2005, the Islands Trust Conservancy installed a rainwater harvesting system for the home at the Ruby Alton Nature Reserve to address a water shortage on the property.  The system compliments the nearby stream supply, able to hold over 60% of the annual water needs for a four person household that practices water conservation.

The site at the Ruby Alton Nature Reserve was designed to model a number of different rainwater harvesting technologies, demonstrating the diversity available to island landowners who are looking for ways to lessen their ecological footprint.  The system cleans the water in three stages before it enters a 6,000 gallon cistern - leaf and large debris removal, sediment removal in catchment pipes, and mesh screen filtration.  Then water travels from the cistern, through a bio sand filtration system and into a day-holding tank, where it undergoes additional particle filtration (to one micron) and rural standard UV light for final disinfection.

For a more detailed overview of the systems components, how it was constructed, and the annual maintenance needed to maintain this rainwater harvesting system, please view the Owner's Manual (pdf).  If you are interested in learning more about the rainwater harvesting system or in touring the demonstration site at the Ruby Alton Nature Reserve, please contact our staff to set up an appointment.

Rainwater - Diagram
 The rainwater harvesting system at the Ruby Alton house
Rainwater - tank
 Surge/pump tank and debris traps at the Ruby Alton house
Rainwater - quality
Comparing quality of creek water with filtered rainwater from the Ruby Alton house rainwater harvesting system

Publications about Rainwater Harvesting

Rainwater Brochure

Collecting and Conserving Rainwater on the Gulf Islands (Brochure)

Island residents and visitors are starting to notice water shortages, and asking why.  This brochure follows the water cycle through the island, showing readers where we're losing water and what we can do about it.  Through pictures and conversation, this resource makes rainwater harvesting easy to understand and fun.
Read more
Rainwater FAQ

Frequently Asked Questions about Rainwater Harvesting in the Gulf Islands

What health and safety requirements do I need to abide by when constructing my rainwater harvesting system?  What are typical system components?  Can I design my own system?  These are answers to some of your more frequent questions.
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Rainwater - Guide

Guide for Regulating the Installation of Rainwater Harvesting Systems - Potable and Non-potable Uses, 2006

These guidelines are intended primarily for use by designers, inspectors and local governments interested in establishing policies related to rainwater harvesting.  They may also be a valuable resource to homeowners considering constructing a system for a single-family dwelling.
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Rainwater - Manual

Owner's Manual: Rainwater Harvesting and Water Supply System

This manual describes the rainwater harvesting system installed at the Ruby Alton Nature Reserve, its features, operation and maintenance and safety guidelines.  Although there are many systems available, this manual gives readers an overview of what types of technologies are available.
Read more

More Information about Water Conservation

If you are considering rainwater harvesting on your island property, the following sites might be useful to you:

Page last updated: 27/10/20
Copyright © The Island Trust Conservancy.     The Islands Trust Conservancy is a qualified donee under the Income Tax Act. Donations are tax-deductible as allowed by law.