Reducing your water bill not only does the obvious -- reduce the amount of money you spend each month for this essential utility -- but more importantly helps to conserve a natural resource. Whether you can cut your bill literally in half depends on how much work you're willing to do, but significantly reducing the monthly bill is an automatic part of water conservancy.
Avoid running the water the entire time you brush your teeth. Turn on the water, rinse your toothbrush, turn the water off, then put paste on the toothbrush and brush your teeth. Use a paper cup to catch water to rinse your mouth and clean your toothbrush. Turn the faucet on again only when you're done.
Recycle shower water. Get a washbasin large enough for you to stand in. Instead of letting water go down the drain, catch it in the wash tub and use it to flush the toilet. You can also pour the water into 2-gal. buckets, and use the to irrigate plants, wash the car or do other cleaning.
Re-use towels. After drying off, hang them on a hook or towel rod and use them several times before laundering.
Institute dedicated laundry days. Instead of doing laundry each day as you dirty it, let it collect as long as is practical. Then, sort all of the clothes into the largest loads your machine will take. On laundry day, also strip all of the beds and wash the sheets together. This will dramatically decrease the amount of water you use to do laundry.
Avoid constant water use when washing dishes. Just like when you brush your teeth, you can scrub your pots with a wet scrubber and soap. You can rinse the pots when they are clean. If you use a dishwasher, always make sure it's completely full before running it. If you have to rinse the dishes before loading it into the washer, fill the sink with water and rinse the dishes in that one sink of water, not in running water.
Check your toilets for leaks. If you find you have a leaky toilet, turn off the water supply until you get it fixed. To flush the toilet, pour a bucket of recycled water into the toilet. This works the same as flushing.