Rainwater Harvesting

We've been researching rainwater harvesting systems for use in our house. What we have found is that most of them are near the range of $30,000. That doesn't quite fit with our model. What we're trying to achieve is an affordable home that couples sustainable building practices and materials with sustainable living. A big part of that is finding ways to avoid the 30% up charge associated with typical sustainable homes. So, we started looking at the alternatives to a $30,000 rainwater collection system.

To start with we looked at the typical water usage of a home. We found that nearly 70% of the water used in a home is for landscaping, outside hose bibs and toilets. So, if we could find a way to cover a huge portion of the water usage at a fraction of the cost of what's available on the market we could help people into sustainability.

We came up with a system that includes a 1,700 gallon underground collection tank and a Master Shield gutter system that filters the rainwater. During a rain the first 10 gallons of water are collected and drained off to remove the huge majority of "undesirables" which is required by code. The rest of the water is collected in the tank. We are introducing a small amount of city water into the tank for the treatment properties it offers.

Water can then be pumped out of the tank on demand using a 15 gpm pump located outside the house. If the tank is drained to less than 250 gallons a valve in the crawl space switches the toilets, hose bibs and sprinklers over to city water. During a pump failure or a power outage the system will also switch over to city water.

Our home monitoring system will show how much water is in the tank and differentiate water usage between collected rainwater and city water. By knowing how much water is being used and how much is available in the tank, homeowners can make small changes to reduce their overall consumption. We will be installing two stage toilets that have the option of a .8 gallon "half" flush or a 1.6 gallon "full" flush which will also help manage water usage.

Our aim is to accomplish all of this for under $8,000. By making the decision to help reduce city water usage by 70% rather than 100% we can offer a savings of $22,000 and we can make it available to many more people.

The overall result of 100 people reducing city water usage by 70% has a much greater positive impact on the environment than 1 person reducing city water usage by 100%. And currently, the number of people choosing a $30,000 system over relying on city water is nowhere near the 1% in that example.