The drought here (following a mild, dry winter) has highlighted the critical need to be ultra water miserly. We already use a lot less water than most families because we pay to truck our potable water in. There's nothing like shortening the feedback loop to make us aware of how much of any resource we are using! When tap water comes from city mains, we just don't conserve as much as when we see the volume of tank water declining each day. In our case, it makes no sense to be using trucked in water for irrigating the garden unless absolutely necessary.
Our solution has been to harvest grey water. I was surprised to discover that we could significantly reduce our water usage by harvesting it and I was SHOCKED at how much water we use just in the kitchen each day. We've always been careful about not using more than necessary but until you have a visual on exactly how much goes down the drain, you just can't quantify it.
Plumbed in grey-water harvesting systems are not permitted here (which is a shame), but I understand the reasons behind it. Grey water can rapidly become blackwater if not distributed immediately so there is the element of health risk when it's not handled, distributed or applied correctly. Through careful engineering and appropriate handing of grey water, lush, abundant gardens can feed families instead of feeding sewer pipes or septic systems!
To get around the municipal barriers to grey water harvesting, I use a dishpan in the kitchen sink to collect produce washing water, cooking water, dishwashing water, etc. It's surprising how quickly this fills up.
In the bathrooms, we use ice cream pails which works very well.
To complement these collection vessels, I've put a 5 gallon bucket just inside the exterior door we use most frequently. It's easy to dump the sink buckets into it as soon as they are full. It's also much more convenient than going outside every time a sink bucket is full. I am astounded at how often that is! A 5 gallon bucket with a handle is also a lot easier to take out and dump (because of the handle) than taking out individual basin bins (which slosh around and end up al over me). I've discovered it's impossible to carry the dishpan full of water out AND open and close the door whereas the handle on a 5 gallon bucket means we can use one had for carrying and the other to deal with the door. MUCH better! Shockingly, most days we can collect between 10 and 20 gallons of grey water from the house to be used in the garden. This is amazing to me coming from only 3 sinks, but we cook a lot and have a slightly larger family.
* A CAUTION about using 5 gallon buckets in your home. Young children can and do drown in very small amounts of water, so I do not recommend using this method if you have young kids. Small kids are very curious and could easily fall into the bucket and be unable to get out (being top heavy and not strong enough to pull themselves out). Use common sense in deciding is this method is appropriate for your family.
An important word about the USE of grey water in the garden. Grey water CAN make you sick if it's used on leafy veggies (lettuce, chard, kale, spinach, etc) or root crops (carrots, beets, onions, potatoes, etc). If you eat any part of the plant that might come in contact with the grey water, do not apply it there.
Grey water is however, PERFECTLY safe to use to water UNDER berry bushes/canes, fruit trees, tomato plants, beans, peas, corn, cucumbers and ornamental flowers, etc. We mostly use ours near the house for convenience sake so that means flower pots, a few trees and berry bushes.
Do you harvest grey water?