Some of the best tips I've found are:
In the kitchen:
- Save water from rinsing vegetables for house plants
- Use the two sink method of dish washing (one with soap and water and one with clean water for rinsing) -- or use a dish washer, which has generally been proven to be more efficient if it's been made in the last 10 years or so.
- Keep cold water in fridge, so you don't run it to wait for it to get cold
- If you have extra ice cubes (like in drinks or that fall on the floor), put them in plants
- Get a water efficient toilet, or put a brick or a bottle of water into the toilet to decrease the amount of water used per flush
- Get a water efficient shower head
- Turn off the water in the shower when you're not actually using it. Many times people say to me "oh but that's not that much time"... Really? Try it. I was amazed at how much time in the shower I was sudsing up, shaving, or just putzing... I think about half the time I'm "showering" I'm actually not using the water. I don't ALWAYS do this, but I try to almost all the time. Sometimes I really need some hot water to sooth muscles or after a long day in creeks of doom, but generally I turn of that water when I'm not using it. It makes a pretty amazing difference, and, hey, you can confuse your friends and pets with your constant starting and stopping.
- I've also heard that "if it's yellow, let it mellow; if it's brown, flush it down" adage. However, I am a semi-germ-a-phobe, and although I know that urine is sterile, I still don't like the idea of it. If you aren't lame like me, though, this is a great way to cut back your water consumption.
- Use a rain barrel to collect water for the yard or plants (often local governments have programs to provide cheap ones, so see if yours does)
- Get plants that are water efficient-- especially for the grass in your lawn, so that you don't have to water it as much. Further, get over your visions of suburban green lawns. They typically cost a TON of chemicals and water (the top water usage in the USA for households is watering lawns-- and most of that water just runs straight off your lawn). Instead, make an AWESOME lawn that has plans that don't need as much water and even think about a rock garden or an edible garden. A truly green lawn is one that doesn't require a ton of chemicals and wasted water (see what I did there? turned that word 'green' right on it's head)
- Go to a car wash that recycles its water or use an waterless home car cleaning like EcoTouch, which is likely cheaper than whatever you're currently using
There are even more tips here. Incidentally, there are also many things you shouldn't flush, including tissues, hair, condoms, and floss! Hmm!