Water Forum
Collection, storage, filtration, and pumps: getting clean, reliable water when there is no tap to turn on.
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What this board is for
Wells, springs, catchment, hauling, storage, pumps, pressure, filtration, and keeping all of it from freezing. Water is the department with the shortest fuse in an off-grid house: without power you are uncomfortable, and without water you have days, less if a freeze turns an outage into damage.
It is also the department that is hardest to fix after the fact, because water is a property of the land rather than something you can add later. A great many of the questions here are really land questions being asked slightly too late, which is why the buying-stage version of them is worth asking early.
The questions that come up most
How much storage do I need? Not a function of daily use alone but of the longest gap you expect between refills, plus a margin for the failure you have not planned for. A low-yield well with a cistern behaves completely differently from the same well feeding a house directly.
Is my water safe? Only a laboratory can say. A basic potability panel covers bacteria and nitrates; beyond that, test for what the region is known for, and repeat after any work on the well.
How do I stop it freezing? Below frost, in heated space, drainable, or heat traced, and heat trace needs power, so design for a freeze and an outage together. The casualty is almost never the tank; it is the pipe stub, the filter housing, or the pressure switch.
Can I legally catch rainwater or reuse greywater? Usually, and it varies by state more than people expect. The laws pages carry what public sources say for each jurisdiction.
What a useful answer looks like here
Say what the source is and what it does: well depth, static level, and yield in gallons per minute if you have a driller's report; roof area and annual rainfall if you are catching; the drive and the tank size if you are hauling. Say what storage exists and where it sits relative to the house, because elevation is free pressure.
For pump questions, give the model, the lift, the pipe run, and the electrical supply, since startup current is what tests an inverter and voltage drop over a long run to a wellhead usually decides the cable size rather than ampacity.
And say where you are. Frost depth, freeze duration, and the legal position on rainwater and greywater all change by state and often by county.
The mistakes that cost the most here
Buying land without establishing what water on it looks like. Solar can be added to almost any parcel; groundwater cannot, and a low-yield well is workable only if you know about it before you design around it.
Pumping on demand from a low-yield well instead of filling storage slowly. The second arrangement lets the well recover, keeps the startup surge off the inverter, and moves the pumping into daylight when the array is producing.
Undersizing the pressure tank, so the pump short-cycles itself to an early death. This is the most common installation error in owner-built systems and it is entirely avoidable.
Buying treatment equipment before testing. A filtration system chosen from a catalog rather than from a laboratory result is an expensive way to solve the wrong problem.
And leaving one piece of the system exposed to freezing. The tank is rarely the casualty; the pipe stub, the pressure switch, and the filter housing at the tank are.
Testing, and what the results actually mean
A basic potability panel covers bacteria and nitrates, which are the immediate health questions. Beyond that, test for what the region is known for: arsenic in parts of New England and the west, uranium and radon in some granite districts, iron and manganese widely, and hardness almost everywhere.
Bacteria results are a snapshot rather than a state, which is why repeat testing matters, particularly after any work on the well and after flooding. Keep the results over time: a file of readings tells you whether something is changing, which a single result cannot, and it is exactly the kind of record that matters when you sell.
Hardness and iron are nuisance rather than health issues, and they are worth treating because of what they do to appliances and fixtures rather than to people. Sulfur smells alarming and is usually harmless. None of that is a substitute for a laboratory saying so about your own water.
Water and the law
Rainwater harvesting is broadly legal across most of the country and actively encouraged in several states, with a handful regulating large-scale collection or potable use. Greywater reuse varies far more: some states have well-developed permitted schemes and many make no distinction at all between greywater and sewage.
In much of the western United States, surface water and sometimes groundwater are governed by water rights that do not automatically come with the land. That is a fundamentally different question from a permit, and it is one to settle before purchase rather than after.
Wells are permitted in most jurisdictions, with construction standards and setback distances from septic components, property lines, and surface water. Those setbacks exist because contamination travels through soil in ways nobody can see from the surface, and they are worth respecting even where nobody is checking.
The laws pages carry the recorded position on wells, rainwater, and greywater for each state and county, with the sources listed and the gaps marked as gaps.
How much of this is regional
Almost entirely. Groundwater depth and yield vary by district, sometimes over a few miles. Rainfall determines whether catchment is a primary source or a supplement. Frost depth sets how deep every line has to be buried, and freeze duration decides whether a pump house needs a heat source.
Water law varies more than any other subject on this site. In much of the west, surface water and sometimes groundwater are governed by rights that may not come with the land; elsewhere a well is a permit and a setback. Rainwater harvesting is encouraged in some states and regulated in others.
Which is why the useful answer to almost any water question starts with where. The laws pages record the position on wells, rainwater, and greywater for each jurisdiction.
Cost, health, and the parts worth paying for
Drilling is the large unknown, priced per foot whether or not good water is found, which is why local driller knowledge is worth more than any national average. Storage is the cheap part and the one most worth over-provisioning, since a cistern bought once solves a slow well permanently.
The health side is not a place to economize. Testing is inexpensive and it is the only way to know what you are drinking; treatment chosen from a catalog rather than from a test result is an expensive way to solve the wrong problem.
And keep one path to drinking water that needs no electricity at all: gravity, stored water, or a hand pump. It is the cheapest resilience measure in the house and the one people are most glad of.
What has already been written about this
Before asking, it is worth knowing what is here. These are the most recent guides on water, each of them long enough to actually answer the question rather than gesture at it. If one of them is wrong, or misses the case you are in, that is an excellent thing to post about.
- Off-grid water treatment for gray areas: nitrates, arsenic
Boiling and UV kill germs but do nothing for nitrates, arsenic, or heavy metals in well water. Here's how to find out what's actually in yours and tre... - Off-grid water treatment methods compared: boiling, UV
Boiling, UV, chlorine, and filters all kill or remove different threats in different ways. Here's how each one actually works, where it fails, and how... - Off-grid water pressure: getting a real shower without a
A weak trickle out of the shower head is one of the complaints off-gridders raise most. Here's how pressure actually works in a tank-fed system, and h... - Testing off-grid water quality: what to check and how often
A tank full of water tells you nothing about what's in it. Here's a real-world testing schedule for wells, rainwater, and springs, plus how to read th... - Keeping off-grid water safe through a hard freeze: pipes
A frozen water system off-grid isn't an inconvenience, it's a crisis. Here's how to actually keep water flowing (or safely shut down) through real win... - Sizing your off-grid water storage: how many gallons you
Off-grid households often guess at water storage and get it wrong in both directions. Here's how to calculate a tank size that actually matches your h... - Drilling or driving a well off-grid: what it actually costs
Thinking a well will solve your off-grid water problem? Here's what drilling or driving one really involves, what it costs, and how to avoid an expens... - How to collect and store rainwater safely for off-grid use
Rainwater can cover most or all of a household's needs, but only if you get the roof, first-flush, tank, and filtration right. Here's how to do it saf... - Gravity water filters vs pump filters: what to actually
Both can save your life, but they fail differently and suit different situations. Here's how gravity and pump filters actually compare for off-grid dr...
The full set is in the water section of the journal, which is updated regularly.
The lesson that covers this
Lesson 3: Water comes first in the free course works through this subject in the order the decisions actually arrive. Size how much you use, pick the source that fits the land, and plan storage and treatment before anything electrical.
The whole course is twelve lessons, free, with no account required to read any of it: start at the beginning if you are new to this, or jump straight to the lesson above if you are not.
Tools for this topic
Most questions on this board come down to a number somebody has not worked out yet. These do the arithmetic and show their working, so an answer here can be checked rather than taken on faith.
- Tools/water usage calculator: turn a household into a daily gallon figure
- Tools/rainwater calculator: work catchment from your roof and rainfall
- Tools/well pump calculator: match a pump to lift and flow
- Specs/pumps: compare pump specifications
How this board works
Posting needs an account, which exists so that answers have a name attached and so that the same person can be asked a follow-up six months later. It costs nothing and it is not used for anything else.
The conventions here are the ones that make a small forum useful. Say where you are, at least to the state or region, because almost every answer on this site depends on climate or on local rules. Say what you have already, and what you have already tried. Give numbers where you have them, and say when you are guessing. And when something works or fails, come back and say which, because the thread is read by far more people than post in it.
Answers here should be able to say where they came from. Experience is welcome and so is a rule of thumb, as long as it is labeled as one. Where a claim is about safety, code, or law, it wants a source, because the reader on the other end may be about to spend money or wire something themselves.
Boards next door
Off-grid questions rarely stay inside one department. A water question is often a power question underneath, and a land question is usually several at once. These boards field the neighboring subjects:
- Sanitation: Composting toilets, greywater, and staying clean and healthy off the grid without a septic hookup.
- Solar & Power: Panels, power stations, batteries, inverters, and wiring: how to make and store your own electricity, and what actually ...
- Land & Real Estate: Finding, vetting, and buying off-grid land and cabins: access and easements, title, perc tests, water rights, zoning and...
- Homesteading & Livestock: Animals, fencing, and the day-to-day of running a productive off-grid homestead.
New here, or not sure where this fits? Start here walks through the whole thing in order.