The largest household use of water is usually outdoor water use, even in places you would normally think of as being quite "wet", people go crazy with their lawn sprinklers every summer.  The best way to reduce water use at home is - get rid of your lawn and plant drought-resistant, native plants.

Nearly half of all water consumed in this country is used to raise livestock, mostly for feedcrops (globally, it's 8%). According to EarthSave International, it takes about 25 gallons of water to grow one pound of wheat compared with about 2500 gallons for one pound of beef. It takes about 660 gallons of water to produce a pound of chicken, including the skin and bones. With the same water, farmers could produce 16 pounds of broccoli, enough soybeans for three pounds of tofu or enough wheat for nearly five pounds of whole wheat bread. Overall, US poultry operations use 96.5 billion gallons of water annually, enough water to meet all the yearly domestic needs of nearly 4.5 million North Americans.

In addition, livestock production is the largest source of water pollution (from animal wastes, antibiotics and hormones, chemicals from tanneries, fertilizers and pesticides used for feedcrops, and sediments from eroded pastures).
It contributes to "dead" zones in coastal areas, degradation of coral reefs, human health problems, antibiotic resistance and much more.

An article in The Guardian exposed that "meat-eaters consume the equivalent of about 1,100 gallons of water a day compared to the roughly 300 gallons used by people on vegetarian diets in developing countries. All that water has to come from somewhere."

So, scientists are finally concluding that it will be almost impossible to feed future generations the typical diet eaten in western Europe and North America without destroying the environment. No kidding. Go vegan.

I think the above post hits it on the head.

You can get a low-flow showerhead, flush the toilet once a day, etc, etc, etc.
But, in ALL these efforts, eating a quarter-pounder will waste WAY more water.

So I think worrying about the little things is a bit silly unless you already have the big things out of the way (i.e. you don't eat meat).

Buy a washing machine with capacity to wash more clothes so that you can wash them on alternate days.  Do you really need a steam iron if you can iron your clothes right after taking them out from the washing machine?  Leaving clothes in the machine will crease them and need more ironing=more energy; the human and electrical type.  Also, when the clothes are still moist, you need less heat and it is easier to iron.  After ironing, hang it up to dry completely instead of using the dryer.  

Use water from washing grains and vegetable and fish to water your plants.  The blood from your fish is a very good fertilizer.  If you are ambitious and use menstrual cup, you can add the collection to your garden too if you are not into painting with it.  Yes, there are people who do that.  

Take showers as a family activity cum biology class for the children.  Pee as your wash your face under the shower.  

Try to use only one toilet in the house so that you need not have to wash all toilets more frequently.  Do not flush the toilet when anyone in the family gets up to pee at night.  Flush only in the morning after all have done their poos and pees.

Stop all sink drips by remembering that it is bad for Feng Shui.  It is like dripping your money away.

If the children have been brought up this way, I think they will be more conscious when they use water in public places.

In Malaysia, the government has started a campaign to construct greener buildings.  One of the suggestions is not to use treated water for washing cars, floors and for gardening.  It rains all year round in Malaysia and collecting rainwater to use for such activities is a better option.

Singapore is more ambitious.  To curtail their reliance of buying water from Malaysia, they are recycling wastewater, or treating sewage water to the point that it is safe to drink.  So, when you are down in Singapore and want to do the "being there done that" thing, make sure you buy a bottle of their NEUwater.

What about fish and those sources of meat that don't pollute large amounts of water?  

I get my water from my well. Any sources for buying a water meter?

Water (or lack thereof) is a huge issue in Australia. As a long time water miser, what has really amazed me has been how quickly the public's mindset has changed in recent years. My home-city of Brisbane, Queensland, is now on level 5 water restrictions, which is the highest level there is (so far). This means restrictions of 140 litres per person per day, with fines for people who exceed this. Washing cars is banned, and gardens can only be watered with buckets, between 4 and 7pm on certain nights of the week. In a city where no more than five years ago it was common to see kids playing under sprinklers on lush green lawns, now every second house has (at least one) rain water tank, and people get chastised by their neighbours if their lawn isn't the same crunchy brown texture as the rest of ours. Of course there are some people who just stick to the rules, or even flaunt them, but I think it's really amazing how quickly most people have changed their outlook and begun to recognise the real value of water.

To follow up my previous post - if you are really serious about saving water, here's some extra tips (in addition to Umbra's excellent ones) from Australia:
Don't hose your garden, in fact, don't hose anything. Throw out your hose right now.
Collect any grey water in your house (from washing dishes, using the washing machine, mopping the floor) and use that on the garden. This requires that you use garden-friendly low phosphate cleaners, which I'm sure we all do anyway.
If you have to clean your car, do it with a bucket on the lawn. Or go to a car wash that uses recycled water.
Even with a low flow shower head, you shouldn't shower for any longer than 4 minutes.
I think the way to make the most difference in your household use of water is to change the way you think about water. If you know that it is valuable, you won't want to waste it.

Re: grassfed beef and chicken: its takes massive amounts of water to grow grass. And they do poop and pee as much as any similar animal.

Re: What about fish and those sources of meat that don't pollute large amounts of water?

ALL animals raised for food pollute. Most of the fish at your grocery store is farmed fish and they are raised in intense confinement, analagous to a veal calf in its tiny cage. Very bad.
Chemicals such as disinfectants, antifoulants and pesticides are used. The most controversial of these is the organophosphorus pesticide Dichlorvos (related to military nerve gases and the most toxic of the Government's 'Red List' substances), used to treat sea lice in salmon farming. It was originally named Nuvan but was renamed Aquaguard as a PR ploy.

Dichlorvos not only kills sea lice, but is highly toxic to all forms of marine life, from plankton to crustaceans, and higher up on the food chain. It is reportedly also harmful to the fish being treated.
Dichlorvos is also a hazard to fish farm workers, who may become poisoned through skin contact and inhalation.

Fish farms also cause intense and highly localised pollution from feces and food pellets. Since salmon cages are generally placed in shallow and sheltered areas with little water movement, the bulk of the waste accumulates beneath the cages. Toxic by-products build up and this toxicity, along with physical smothering, cause destruction to natural organisms and can change the whole balance of the ecosystem.

Then there's the matter of nitrates, phosphates and nitrogenous waste products (eutrophication). Eutrophication encourages population blooms of phytoplankton, some of which produce highly toxic substances. These can cause mass mortalities of fish and other wildlife, and are associated with paralytic shellfish poisoning in humans. I just read that a US study has shown that a 20 acre salmon farm produces as much organic waste as a town of 10,000 people!

Think about it ...

The best thing to do for the planet and the animal victims is to eat a PLANT-BASED DIET. It's that simple.