Tiny House Water Systems: Off-Grid Collection & Filtration

Start by tracking how much water you actually use. Most tiny house couples land between 40 and 80 gallons per day. Heavy users who shower longer, do laundry on-site, or run a flush toilet can hit 80 to 100 gallons.

Add laundry (20 to 30 gallons per load) or a flush toilet (15 to 30 gallons per day) and daily use climbs fast. A composting toilet is one of the biggest water savers for off-grid living.

Low-flow fixtures make a real difference. A standard shower head uses 2.5 gallons per minute. A low-flow head uses 1.5 GPM or less. Faucet aerators drop sink flow to about 0.5 GPM. These changes can cut water use 30 to 50% with no real loss in comfort.

Three Water Sources

Rainwater — You collect runoff from your roof into storage tanks. Works well in areas with steady rainfall. Low running cost after install. You need enough roof area and storage to get through dry spells.

Well — You drill into the ground and pump water up. Gives steady supply year-round in most areas. Higher upfront cost. Needs electricity or solar to run the pump.

Spring — If you have a natural spring on uphill land, gravity can deliver water to your house with no pump. Rare, but ideal when available. You still need filtration and legal rights to the water.

Rainwater systems catch roof runoff, store it in tanks, and filter it before use. They work best where you get at least 20 inches of rain per year and have enough roof area.

A well gives you groundwater that does not depend on rainfall. Once drilled, a good well can last decades. The main cost is upfront — drilling and the pump system.

Well Drilling

Drilling costs $15 to $50 per foot in most areas. Total depth depends on your local water table.

Shallow well (25 to 80 feet) — $3,000 to $8,000 total. Works where the water table is high. More risk of contamination and seasonal dry-up.

Deep well (100 to 300 feet) — $8,000 to $20,000 total. Better water quality and year-round flow in most regions. What most off-grid owners need in areas without a shallow aquifer.

You need a permit before drilling in almost every state. A licensed driller handles the work. The well gets cased with steel or PVC pipe and sealed to keep surface water out. Test the water before you drink it — bacteria, nitrates, and minerals vary by location.

Well Pump and Pressure

Submersible pump — Sits below water level in the well. Quiet and reliable. Costs $400 to $2,000 depending on depth and flow rate. Most tiny houses need 0.5 to 1 horsepower.

Jet pump — Sits above ground. Only works for shallow wells under 25 feet. Cheaper ($300 to $800) but noisy and needs freeze protection.

Pressure tank — A 20 to 40 gallon pressure tank ($150 to $500) stores pressurized water so the pump does not cycle on and off every time you open a faucet. Keeps pressure at 40 to 60 PSI like a normal house.

Solar well pump — Runs directly from solar panels or from your battery bank. Costs $800 to $3,000. Good for off-grid properties. Pair with a large storage tank so you have water when the sun is not out.

Springs

A spring on your property can feed your house by gravity if the spring sits uphill from your build site. You need at least 1 to 3 gallons per minute year-round. Build a small collection box at the spring source with a screened intake and overflow. Run buried pipe to a storage tank or directly to the house.

Check water rights before you develop a spring. Many western states treat spring water as a regulated resource even on private land.

Never drink untreated water from a roof, well, or spring. Filtration and testing are not optional. Even clear water can carry bacteria, viruses, or chemicals you cannot see or taste.

Three-Stage System for Drinking Water

Stage 1: Sediment filter — Removes sand, rust, and debris. A whole-house sediment filter ($50 to $150) protects pumps and downstream filters. Replace cartridges every 3 to 6 months.

Stage 2: Carbon filter — Removes chlorine taste, many chemicals, and odors. Carbon block filters cost $100 to $400 for the housing plus $20 to $60 per replacement cartridge. Replace every 6 to 12 months.

Stage 3: UV sterilizer — Kills bacteria and viruses with ultraviolet light. UV units for tiny house flow rates (6 to 12 GPM) cost $400 to $900. Replace the UV lamp once a year ($80 to $150). Water must be clear for UV to work — sediment filter must come first.

A three-stage sediment + carbon + UV system costs $800 to $1,800 installed. Budget $150 to $300 per year for filter and lamp replacements.

Optional: Reverse Osmosis

Reverse osmosis (RO) removes dissolved minerals, fluoride, arsenic, and many chemicals. Install an under-sink RO unit ($300 to $900) for drinking and cooking water only — not whole-house use. RO wastes 3 to 5 gallons for every gallon it produces. Replace RO membranes every 1 to 2 years.

Gravity Filters

Berkey and similar gravity-fed ceramic filters ($200 to $400) need no electricity. They filter 2 to 4 gallons per hour and work well as a backup or for drinking water only. Filter life: 3,000 to 6,000 gallons.

Water Testing

Test new water sources before you drink. Basic bacteria and nitrate tests cost $50 to $100. Full panels including metals and chemicals cost $200 to $400. Test once a year after that. Your county health department or a certified lab can run the tests.

Rainwater Laws

Rules vary by state. Most eastern and midwestern states allow residential rainwater collection. Some western states limit collection because of water rights laws — water that hits your roof may legally belong to downstream users in those states.

Texas, Ohio, and Virginia actively support rainwater use. Colorado, Utah, and Nevada have restrictions or registration requirements. Always check your state and county before installing tanks.

Well Permits

Nearly every state requires a permit to drill a well. Your county health department or water agency handles this. Expect a fee of $50 to $500. Wells must meet setback rules from septic systems (usually 50 to 100 feet). Water testing is required before use in most counties.

Common Mistakes

Sizing storage for average use instead of dry-season shortfalls. Skipping the first-flush diverter and getting poor water quality from roof debris. No backup plan when a pump fails or a drought empties the tank. Drinking untreated well or rainwater water without testing. Installing tanks before checking if rainwater collection is legal in your county. Using a pump that is too small for your well depth. Forgetting that UV filters only work on clear water — clogged sediment filters must be changed on schedule.