Why greywater?

We live in the Pacific Northwest where we have the good fortune of an abundance — some might say overabundance — of rain. But not all climates are so fortunate. Some parts of the world have almost constant water shortages due to degradation of the local water supply or a population which exceeds the water capacity of the region. Even in the northwest, we have to occasionally worry about drought, and no one likes high summer water bills.

On the other side of the coin, most homes in the US dump hundred of gallons of water into the sewer system every week. Some of this water is blackwater, which is any water that contains high levels of pathogens, e.g., toilet water. But the vast majority is greywater, which is water that has only a small amount of contamination, such as laundry or hand-washing waste water. Since black and greywater are mixed in most sewage systems, municipalities have to invest in expensive treatment plants which treat the whole slurry as if it were blackwater.

So here we have two problems: water shortages and sewer system load.

As is often the case, this problem can be mitigated by turning waste into a resource:

By separating out greywater from blackwater, we can reduce our residential water usage and reduce the load on our sewer systems. It’s a win-win!

In the next posts, I’ll give a high level overview of some of the concerns around greywater reuse and some practical tips about greywater systems.

In this post and throughout the rest of this series, I use Art Ludwig’s The New Create an Oasis with Greywater as my primary source; it’s considered one of the best resources on residential greywater for the lay reader. Other bits and pieces are mostly pulled from my memory of other books and websites I’ve read. Any mistakes are, of course, my own.