I just looked at www.weather.com and discovered that my city averages only 1/2 an inch of precipitation in May, and even less than that in June - September.
There is a drought in my area and even tap water can be expensive. I am going to need to find ways to maintain a necessary amount of water for the plants, without going broke. The cost for the privilege of having running water in my house is $30 / month. Any amount of water that I use is added to that amount.
My first idea is to reuse water from the house. If I wash my hands with a biodegradable soap then I can put that water on the compost pile. When I do not use soap, I can catch that water in a basin to water plants. I can also just rinse my hands with a washrag when that will be sufficient, like when they just have a little dirt on them and I am going back outside anyways.
Another thing I can do is divert washing machine water to an area outside. I could also hang my clothes to dry outside near the plants. If spaced closely together that might provide a little bit of humidity, which may decrease the plants' need for water.
I can catch water in the shower while I am waiting for it to warm up. If I want to work a little harder then I could also catch the water used while getting wet before using soap. If I use biodegradable soap and shampoo then I can catch the soapy water separately for use in the compost pile.
I could catch rain from my roof to store it for non-rainy times. I do not know how much it would cost for a rain barrel and to retrofit my water spouts to catch the water. It might be worth it.
I could also create small ditches to help catch water and allow it to flow into the ground. These small ditches could be filled with rocks to become a path. This is a way to catch runoff. It also helps keep the ground moist in hot weather. This probably wouldn't become too water-logged since the highest average rainfall is less than 5 inches/ month.
Finally, I can utilize mulch and shading to help the plants retain the water they have. Also, the compost bin does not have to have water when there isn't any available. It can wait until the rain comes. Besides, additions of water containing food scraps will maintain some moisture. I can also cover the compost pile to deflect sunlight.