Start with demand

Every water system answers one question: can supply keep up with demand? Demand is the water your household uses.

Most people have no idea how much water they use. On city water, it just comes out of the tap. On a homestead, every gallon has to be caught, pumped, stored or carried.

So the first step is not choosing a tank. It is measuring what you use. Everything else in this track builds on that number.

The national picture

The EPA estimates that the average American uses about 80 gallons (300 liters) of water a day at home. A typical family can use around 300 gallons (1,100 liters) a day.

Those numbers include two kinds of use:

• Indoor use: toilets, showers, taps, laundry and dishes. This happens all year.
• Outdoor use: lawns, gardens, washing cars, pools. This peaks in summer. Nationally it is about 30 percent of household use, and much more in hot, dry places.

Averages hide a lot. Your number depends on fixtures, habits, climate and how big your garden is.

Where indoor water goes

Researchers have metered thousands of homes to see where water goes. The share for each use shifts between studies, but the order stays fairly steady.

In a typical US home, toilets are the largest indoor use. Showers, taps and clothes washers follow. Leaks come next, and they are often larger than people expect.

Fixtures make a big difference

A fixture is anything water flows out of: a toilet, shower head, tap or appliance. Its flow rate is how fast it uses water, in gallons per minute (gpm) or gallons per flush (gpf).

Older fixtures can use two or three times more than newer efficient ones. An old toilet might use 3.5 gallons (13 liters) or more per flush. Many newer ones use 1.28 gallons (about 5 liters) or less. EPA’s WaterSense label marks fixtures that meet its efficiency criteria.

On a homestead, every gallon you save is a gallon you never need to catch, pump or store.

Homestead use is often lower

Households on rain tanks or hauled water often use much less than the national average. The Texas rainwater manual puts a water-conserving household at about 25 to 50 gallons (95 to 190 liters) per person per day. Some careful households use less. It depends on fixtures and habits.

They get there with efficient fixtures, shorter showers, full laundry loads and fixing leaks quickly. Some use composting toilets, which use little or no water.

Outdoor water and climate

Outdoor water is where climate changes the answer most.

In a humid place with regular summer rain, a garden may need little extra water. In a hot, dry place, the same garden may need more water than the house does. Summer is also when rain is often scarce.

That means your peak demand and your lowest supply may land in the same months. Keep indoor and outdoor use as separate lines in your plan. You will see why in lesson 20.

A quick estimate

If you cannot measure, you can estimate. For each use, multiply how often by how much:

• Showers: minutes per day × shower head flow (gpm)
• Toilet: flushes per day × gallons per flush
• Laundry: loads per week × gallons per load ÷ 7
• Kitchen and drinking: often a few gallons per person per day

Add them up per person, then multiply by the number of people. Add outdoor use as its own line, and note which months it applies to.

Check

Summary

• Demand is the water you use. Measure or estimate it before sizing anything.
• The EPA puts the average American at about 80 gallons a day at home. Homestead households often use far less.
• Toilets, showers and faucets use most indoor water. Leaks are a hidden user.
• Outdoor use depends heavily on climate and often peaks when rain is lowest.

Next, you will compare where water can come from.