One of my many obsessions is seeing JUST how little water I can use to sustain my gardens and clean my clothes and dishes since water crisis is now the norm for Florida, with permanent water use restrictions we could have NEVER imagined in the 60s and 70s. A 4 gallon bucket beneath my kitchen sink does wonders to help me meet that fun goal.
I have been using this method since the early 90s in Denver, and for several years here in Tampa, both times due initially to my reluctance to do "home improvement" tasks as they nearly always become so difficult (especially plumbing!) that I get all pissed off....and I am rarely grumpy. In both cases, the trap beneath my kitchen sink sprung a leak, so I put a bucket beneath it "until I fix it". Yeah right. Me? Procrastinate?
Both times I chose to NOT fix it at all due to quickly becoming enamored with seeing my kitchen water use quantified vs. just "disappearing down the drain". Both times I kept overflowing the buckets as I simply had NO idea JUST how much water I had been using all my life to wash dishes....if you try this method DO get a deep tray to put beneath the bucket for the inevitable overflows until water wise dish washing becomes instinctual and habitual. Here I have a plastic tray that I THINK was the base for a kitty litter box beneath the bucket. Having done this for so many years I now rarely overflow the bucket. Once you disconnect the drain pipes, be sure to stuff a used plastic grocery sack into the outflow pipe to insure that "sewer gas" (methane) can't back up into your home as it is explosive.
When I want to scrub the sink down with Comet I dump the bucket's contents in the garden, replace the bucket, then clean the sink good.....THAT water gets dumped into my toilet, where I use it again to scrub and clean the bowl. The key is to use the water TWICE. Use it once to wash your dishes, then again to nourish plants in your yard and gardens. Once to scrub the sink, and again to scrub the toilet bowl.
Just be sure to use a low-sodium dishwashing liquid like 'Sun & Earth' brand since you will be using your graywater on plants....many "earth friendly" soaps are LOADED with sodium vs. phosphorus, which I would prefer since it is a plant nutrient many soils are low in. That is one reason I do not salt the water I cook pasta in then drain in a colander in the sink.
Why go through all this "hassle" after a lifetime of ignoring the water's effortless spiralling down the drain? It has helped me to DRAMATICALLY lower my water use and hence water bills at both homes....last June, this practice is partly why my total water use bill was $1.35 despite all the agriculture plus laundry and dishwashing I do here. The bits of food scraps in the graywater act as soil foods to boost my fertility for free. Quantifying the water in a 4 gallon bucket is a potent reminder that the world is increasingly short of safe clean fresh water. Carrying the bucket to dry areas in my yard, or to thirsty plants like my papayas, guava and bananas, is good exercise. But most importantly to me is that all over this planet, many many millions of people have to walk miles to GET then BRING HOME the water they need to meet their families' most basic needs. So the least I can do is walk 70 feet or so to a thirsty rose or fruit tree to reuse my kitchen graywater.
I keep a 5 gallon bucket in the kitchen so that as the sink bucket starts to get full, I can slip it out of the cupboard and dump it into that bucket, then put it back so I can continue washing dishes. I then take the 5 gallon bucket to where the water is needed.
Some folks can afford to spend thousands on high tech kitchen gray water recovery systems......I'll stick with a 4 gallon bucket and plastic tray I rescued from a dumpster as an easy yet very effective way of incorporating a key principle of permaculture into my urban farm.....re-use, recycle, don't waste.