Water decides where your house can go. Before the floor plan, before the solar panels, before the garden, you need to know where your water comes from, how much you have, and what the county will accept.
The good news: water is the most forgiving system to get right if you plan it early, and the most expensive to fix if you don't. This lesson walks you from your family's real daily use, to the three ways a homestead gets water, to how to size storage that carries you through a dry summer.
- 1Measure how much water your family actually uses in a day.
- 2Compare wells, rooftop rain and other sources for cost, reliability and approval.
- 3Calculate how much rain your roof can catch in a year.
- 4Size a storage tank for your dry season.
- 5Know the point where the county gets involved, and what to ask.
How much water do you really use?
Most families have no idea. The EPA estimates the average American family uses more than 300 gallons a day at home, and about 70 percent of it indoors. On a homestead, every one of those gallons has to be pumped, caught, stored or hauled, so the first and cheapest water system is simply using less.
75–150 gal
per person, per day, when water is cheap and endless.
30–50 gal
per person, per day, with efficient fixtures and habits. A planning figure, not a rule.
Where the big savings are
- Toilets are often the single biggest indoor use. A low-flow or composting toilet (Lesson 3) can cut household water dramatically.
- Showers are a flow-rate problem. A 2 gallon-per-minute head and a 5-minute shower is 10 gallons. A 20-minute shower is 40.
- Leaks are silent. A running toilet can waste more than your whole family drinks.
- Gardens are seasonal giants. Outdoor use spikes exactly when rain stops, which is why storage and soil (Permaculture Design) matter so much.
Where homestead water comes from
Almost every rural home relies on one of three sources, or a mix. The right choice depends on your land, your rainfall and your county.
Private well
Good for: a steady year-round supply, and the source most counties expect for a new home.
Watch for: drilling cost and depth are unknown until you drill; water quality needs testing.
Rooftop rain
Good for: gardens, animals, washing, backup and fire storage. Free water from a roof you already have.
Watch for: rain is seasonal, so storage is the real cost; drinking it needs treatment.
Springs, streams, hauled
Good for: supplementing other sources where rights and access allow.
Watch for: surface water needs water rights in many states; hauled water may not satisfy a permit.
Wells
In California, domestic wells are permitted by the county, usually the environmental health department, and must be built to the state's well standards by a licensed C-57 well driller. A typical new domestic well project often runs about $15,000 to $45,000 including the pump and pressure tank, and the process commonly takes two to four months, mostly waiting on the permit.
- Ask well drillers what depths and yields neighbors got
- Ask the county for nearby well logs, where available
- Keep septic and animal areas at least 100 ft away, and downhill
- Budget for a yield test and a water-quality test
Many counties want proof your well can supply a home before they issue a building permit. Santa Cruz County, for example, asks for a sustained 3 gallons per minute over 24 hours of pumping, or 2 gallons per minute in late summer, plus passing water tests. Ask your county for its exact standard.
Rooftop rain
California's Rainwater Capture Act of 2012 made it clear: collecting rainwater from your roof does not require a water right permit. There is no state limit on how much you can store, and a 2018 law gave a property tax exclusion for new rain capture systems. Plumbing it into a house, especially for drinking, is a different question that goes through the plumbing code and your county.
In most places, plan a well for the house and rain for the land. Let the roof feed garden tanks, animal water and fire storage, and let it overflow into swales and a pond. You get a resilient system and a beautiful landscape, without asking the county to approve rain as your only drinking water.
The rain math
This one formula will guide every water decision you make:
One inch of rain on one square foot of roof is about 0.623 gallons. Use the roof's footprint from above, not the curved or sloped surface. Then plan to keep about 80 percent, because some water splashes, evaporates or gets dumped by the first-flush diverter.
A 20 × 20 ft home has a 400 sq ft footprint. In a place with 30 inches of rain a year:
400 × 30 × 0.623 × 0.8 ≈ 5,980 gallons a year
That's about 16 gallons a day on average. It's wonderful for a garden and animals, and nowhere near enough for a family of four using 50 gallons each. The math tells you what each source is for.
Rain versus need
Find your rainfall from your county, a nearby airport, or NOAA's climate data. Use a dry-year number, not an average, if rain is your main supply.
Storage: carrying the dry season
Rain rarely falls when you need it. Across much of the West, nearly all of it comes in winter and almost none in summer, exactly when the garden is thirstiest. Storage is how you move winter water into July.
How to size a tank
- Count your dry months. How many months in a row get little or no rain where you live?
- Multiply by what rain must cover. Gallons per day for the jobs rain will do, times 30, times the dry months.
- Check it against the catch. You can't store more than your roof collects, so a bigger roof sometimes beats a bigger tank.
A garden that needs 60 gallons a day through a 5-month dry season needs about 60 × 30 × 5 = 9,000 gallons of storage. That's more than the 400 sq ft roof above catches in a year, so this family either adds roof area (a barn or carport roof), reduces garden watering with mulch and swales, or tops up from the well.
Pressure and gravity
Every 2.31 feet of height gives you 1 psi of water pressure. A tank 23 feet uphill gives about 10 psi — fine for garden hoses and drip lines, but a house usually wants 40 to 60 psi. That's why most homes use a pump and pressure tank, and why a tank on a hill is still a great way to water the garden with no power at all.
Clean water and the county
The county gets involved the moment water reaches people: drilling a well, plumbing a house, or using any source for drinking.
| What you're doing | Usually needs | Who to call |
|---|---|---|
| Barrels or tanks for the garden | Often nothing for tanks on grade up to 5,000 gallons (Lesson 1); check zoning and fire rules | Building department |
| Drilling a well | Well permit, licensed driller, sanitary seal, setbacks | County environmental health |
| Rain plumbed into toilets or laundry | Plumbing permit for an alternate water system | Building department |
| Rain or spring water for drinking | Treatment, testing and county approval, where allowed at all | County environmental health |
| Permit for a new home | Proof of an adequate, safe water supply | Both, before you buy |
Test, then test again
Private well owners are responsible for their own water quality. A common recommendation is to test every year for coliform bacteria, nitrate and dissolved minerals, plus any local concerns such as arsenic. Basic tests often cost around $100 to $400.
Questions to ask before you buy
- What does the county require to prove water for a new home on this parcel?
- Are there well logs or yield records for nearby parcels?
- Will you accept rainwater for any indoor uses? For drinking?
- Does the fire district require a water tank for new homes here?
- Are there groundwater limits or a local water agency I should know about?
The family water audit
Turn your house into a water lab. For one full day you'll measure every gallon your family uses, then catch real rain from your own roof and see how far it would go. Most families are surprised by both numbers.
You'll need
- A 5-gallon bucket and a phone timer
- A tally sheet on the fridge
- A tape measure
- A rain gauge, or a straight-sided can
- Optional: your water meter or bill
Do it together
- Measure flow. Time how long the shower and kitchen tap take to fill the bucket. 5 gallons ÷ minutes = gallons per minute.
- Tally a day. Count every flush, time every shower, and count dishwasher and laundry loads.
- Add it up. Toilets use about 1.3 to 3.5 gallons a flush (check the label). Divide your total by the number of people.
- Measure your roof footprint. Walk the outside of the house and multiply length × width.
- Catch a storm. Read the rain gauge after a storm and use the rain math to find how many gallons your roof shed.
- Make a plan. Pick three ways to cut use, and decide what rain on your land should be for.
Little scientists
- Hold the bucket and call out when it's full
- Keep the tally marks for flushes
- Check the rain gauge each morning
Older scientists
- Calculate gallons per minute and per person
- Make a bar chart of where your water went
- Use the calculator above to test three roof sizes
Keep the tally sheet and chart. They make excellent evidence of learning for your records.
Water is the first thing you tend
Every homestead story begins with water: where it falls, where it gathers, how it's kept clean and shared. Get to know yours before you build, and the rest of the design starts to fall into place — the house near the well, the tanks uphill from the garden, the overflow filling a pond where the kids will catch frogs.
In the next lesson we follow the water out the other side: septic, composting toilets and greywater, and how to turn what leaves your house into something that feeds the land.
Your Lesson 2 worksheet
Work through these together. Your answers save on this device as you type, and print cleanly for your records.
Progress record
What this lesson practices:
- MathRates and unit conversions, multiplying decimals, and multi-step word problems (Common Core 5.NBT.B.7, 6.RP.A.3).
- ScienceThe water cycle and how water is stored and distributed on Earth (NGSS 5-ESS2-2, MS-ESS2-4).
- DataCollecting measurements, tallying, and making bar graphs (Common Core 3.MD.B.3, 6.SP.B.4).
- Life skillsHousehold budgeting of a resource, conservation, and planning.
Standards mapping is a draft. If you use charter or ESA funds, confirm it with your education specialist.
Sources for this lesson
- California Water Code §10574 — Rainwater Capture Act of 2012
- AB 1750 — Rainwater Capture Act of 2012 (bill text)
- EPA WaterSense — How we use water
- California Water Boards — Guide for private domestic well owners
- DrillerDB — California well drilling costs and permits
- Santa Cruz County — individual water system requirements
- MyRainPlan — rainwater harvesting laws by state