In summers we have to deal with power outage and shortage of water. Dealing with former is not that hard. The backups do their work fine and we usually get by. But water shortage is a serious problem.
The first and one of the most effective techniques was discovered by my mother. While washing clothes she used to throw away residual soap water down the drain. Now she collects the water in a bucket and uses it for cleaning. Soap water is excellent for wiping floors and cleaning your bathrooms. It is also good for cleaning away dust in general. Just take a piece of unused cloth. Dip it int the collected soap water and you can use it to wipe stains of surfaces. On an average she saves about six buckets of water in a week. We never clean our floors using fresh tap water any more.
The tap water is not usually fit for drinking as it is. Like most people in our neighborhood we filter it using RO filtration technique. On an average, for a family of four, the filter will spit out 2 buckets of water a day. This water though unsafe for drinking can be used for other purposes like bathing, cleaning utensils and watering plants. Initially I noticed that most our neighbors threw away this water down the drain. But now we collect it and it helps a lot.
A similar technique can be used to collect water draining from air conditioners. Although it might not seem much but collecting water from different sources quickly adds up and you will have plenty to use in various household chores.
The third technique that I use is rain water harvesting. In my country, India, we have monsoons. When it rains it pours. My ancestors were pretty good at rain water harvesting. In fact it was a necessity. There was a very effective drainage system running though the town that used to collect the rainwater into very large depressions that were made for this purpose. The principle was simple. The roads were made at a higher ground with a slightly sloped angle emanating from a common depression in an area. There were numerous depressions within the city. So every part of the city had it's own reservoir of water and sloped roads which acted like feeders to it. It was quite clever and worked well for it's time. However as our town grew this system was done away with, without employing any alternative method of rain water harvesting.
So the trick that I use is somewhat similar to what my ancestors used in their days. We have a roof with a slightly sloped flooring and a single point of drainage through a plastic pipe. When it rains the water flows from the slope into the pipe and we collect it at it's opening below. During moderate rainfall I have collected 1000 liters of water in 15 minutes. That is a lot! In fact the only reason that I stopped was because I ran out of containers to keep water in.
I am brainstorming on different ideas to help me collect more water with minimum cost. Of course collection of water solves just a part of the problem. If there were a simple solution to filter it and make it fit for drinking then the amount of water that rains during one season of monsoon could satiate thirst of my neighborhood for the rest of year.