How much water does the typical family use? Probably a lot more than they need to. Here are some estimates of the typical water usage:
Average Adult or Child = 50-100 gal./day
Clothes Washing Machine = 30-50 gal./use
Shower/Tub = 25-60 gal./use
Toilet = 4-7 gal./use
(source: USDA Water Systems Handbook)
These are probably rather high estimates. But water is not something that you want to underestimate. One thing to decide when setting up your water system is, how conservative are you willing to be with water usage. The largest offender in water consumption is the irrigation of one's garden and lawn. While watering your lawn could be something you are willing to give up, a garden is very critical, and irrigation is key for good productivity. Information on low water consumption irrigation systems. If one is careful with water usage, the figures above can be improved upon. Using the minimum figures from the USDA, 3 adults would empty our 1,200 gal. cistern in approximately 4 days or less. In actuality, it usually lasts three of us 5 or 6 days. PLEASE BEAR IN MIND, though, that this is only domestic use. Irrigation for agriculture can be quite vital to success in many climates. Depending upon your needs and the climate you are in, this could take 2,000 gallons per day or more for an orchard, garden, and domestic use combined. Please do not overlook this important consideration. Water truly is "liquid gold"!
Another topic to consider is how to conserve water. A few very simple ways that do not affect your lifestyle are switching to a conservative toilet, using a shower head that that yields a good shower with less water, and using a Staber Washing Machine. Also, making sure that the washing machine is on the "large load" setting only when it truly is a large load. And as mentioned above, low water consumption irrigation is very critical. That is where you can experience some major water savings.