(This is the first of an at least three part series about ways in which renters can reuse greywater. For a definition of greywater, and why it’s a good idea to recycle it, check this out.)
When I first moved to Portland five and a half years ago, I was really impressed by the ways that I saw folks reusing water, especially from kitchen and bathroom sinks, without the elaborate remediation systems more commonly talked about. Most of the systems involved little to no modification to plumbing, and those that did were to a degree that I personally feel comfortable doing without consulting the landlord (more on this below).
Greywater reuse generally falls into two categories, interior (household) and exterior (landscape). In the first couple of posts in this series, I’ll address interior uses that are feasible for most renters. After those, I’ll follow up with a post about exterior uses.
The P Trap Disconnect for Toilet Flushing
Almost all sinks are outfitted with a p-shaped section of pipe below the drain. The purpose of this fitting, called a p-trap, is to mitigate the backflow of sewer gases. Because the p-trap always stays full of water, gases that would otherwise rise up through the drain cannot pass. Disconnecting the p-trap under a sink and placing a 3 gallon bucket (or similarly sized container) under the drain pipe, is an easy way to catch greywater for any sort of reuse. (If you use something much larger than 3 gallons, it gets too heavy when full.)
Drop Your Household Water Use by 25%, Instantly
Flushing the toilet with greywater is one of the easiest ways to make an enormous dent in your water use—toilet flushing accounts for over a quarter of household water use. With a P-trap disconnect system, all you have to do to flush the toilet is take the bucket from under the sink and pour it into the toilet bowl. The weight of the water you pour in opens the diaphragm that drains the bowl, the same way that the weight of the water in the flush tank does when it is released. In my experience, the amount of water that ends up in the bucket daily is usually enough to flush the toilet when it is needed, and if you regularly end up with the bucket full before someone has needed to flush, you probably want to assess your water use at that sink. With the p-trap method, water that would otherwise be used once now serves two functions, and you don’t have to contaminate a couple gallons of fresh water every time you flush.
For a photo tutorial on how exactly to disconnect a p-trap, check out this page from the Greywater Guerillas.
After you’ve gone through the tutorial, find a wrench and a bucket and get to it. Try it out for a week and let me know what you think. My guess is that you’ll find that it’s not a major inconvenience. Having to go through the act of lifting, moving, and pouring the flush water really gives you an appreciation for how much fresh drinking water goes down the toilet every time we flush.