Subject

Water Management

Water management is the practice of catching, storing, moving and cleaning your own water, so that a household or a holding has what it needs without depending on a mains supply.

It's the first system to get right on any piece of land, because every other one assumes it's already working.

The first system, and the one nobody plans

Ask what a place needs and most people start with shelter or power. Water beats both. You can sleep rough and you can live without electricity, but three days without water settles the question for you, and every other system on a holding, growing, livestock, sanitation, washing, fire control, is downstream of this one.

A tap makes water look like a utility, something that arrives. It isn't. It's a catchment, a store, a route and a treatment step, and a mains supply is simply somebody else operating all four on your behalf. Learning the subject is mostly learning what those four are doing, so you can run them yourself when you need to.

If the supply stops, or the pump fails, or what comes out of the tap stops being safe, the household that already knows where its water comes from and how to make it drinkable is in an entirely different position from the one finding out.

Where the water comes from

Every source has a different failure mode, and that's the reason to have more than one. A holding with a single source has a single point of failure.

  • Roof catchment.The most predictable, because you can calculate it: roof area multiplied by rainfall gives volume, and the arithmetic works anywhere. The catch is that it stops when the rain does, so it lives or dies on storage.
  • Wells and bores.Steady, largely weather-proof, and the most work to establish. Depth, yield and water quality vary enormously over short distances, so a neighbour's well tells you something and guarantees nothing.
  • Springs.The prize where you have one: gravity-fed, continuous, and needing no pump at all. Protect the spring head from stock and surface runoff or you've inherited a contamination problem along with the flow.
  • Surface water.Creeks, dams and ponds. Easy to reach and the most likely to carry pathogens, silt and whatever the catchment above you does, so it needs the most treatment.

Catching what falls on the roof

Roof catchment is where most people start, and it rewards a small amount of care at the front end.

The first flush off a dry roof carries dust, bird droppings, leaf litter and whatever settled since the last rain. A first-flush diverter sends that opening volume to waste before the tank starts filling, and it does more for water quality than any treatment step further down. Screen the gutters as well, because organic matter in a tank is what turns a store into a culture.

Roofing matters. Any surface can shed water, and some shed things you don't want with it: old lead flashing, bitumen, and paints or treatments not meant for potable catchment. If you're unsure what the roof is coated with, treat the water as non-potable and use it for irrigation and washing while you find out.

Storage, and why it is the real constraint

Catchment is easy. Storage is what costs money, and it's what decides whether you get through the dry stretch.

Size it against the longest gap between useful rain in your area, not the annual average. An average conceals the six weeks that actually break you. Work out the daily draw for everything the household does, multiply by the length of the dry run you want to survive, and that's the tank, whatever the rainfall figure says.

Keep light and warmth out of the store. Algae needs light, and most of what grows in a tank grows faster warm. An opaque tank, shaded or buried, does more for keeping the water sound than anything you add to it. Screen every opening, including the overflow, because a tank is also an attractive place for insects and small animals to get into and not out of.

Split the storage if you can. Two tanks plumbed together can be isolated, so one can be cleaned, repaired or quarantined after contamination while the other keeps working. A single large tank is a single large failure.

Moving it without a pump

Gravity is free, silent, needs no fuel and doesn't break. Where the ground gives you any fall at all, use it.

The two numbers are head, the vertical drop, and friction, which is what the pipe takes back. Head is what gives you pressure, and every metre of drop buys a fixed amount of it. Friction rises sharply as pipe diameter falls, so a longer run of wider pipe frequently delivers more than a short narrow one, and undersized pipe is the most common reason a gravity system disappoints.

Where pumping is unavoidable, the question is what happens when the power isn't there. A hand pump on the well, a header tank filled when power is available and drawn down by gravity when it isn't, or a ram pump using the flow itself, all keep water moving through an outage.

Making it safe to drink

Treatment is a sequence, and each step does a job the others can't. Skipping to the last one is the usual mistake.

Settling and filtering come first, because they take out the silt and organic matter that would otherwise shelter organisms from whatever you do next. Cloudy water defeats both chemical treatment and ultraviolet light, so clarity is a precondition and not a preference.

Then disinfection. Boiling is the most reliable method available anywhere, needs no supplies, and costs fuel. Chemical treatment works and depends entirely on getting the dose right for the strength of what you actually have, which is why it's read off your own container rather than off a number in a book. Ultraviolet and fine ceramic or membrane filtration both work well on clear water and both have limits worth knowing before you rely on them.

What treatment can't fix is dissolved chemical contamination. Boiling concentrates it. If there's any question about what's upstream of a source, that's a testing question, not a treatment one.

Drainage & Greywater

Water leaving the house is the half of the subject that gets ignored, and it causes as many problems as the supply does.

Greywater is what drains from washing, laundry and the kitchen. It carries soap, fats and food matter, and it will turn septic within a day or two if it sits. Used promptly it irrigates well, particularly on trees and non-food plants, and the practical rule is to get it out to where it's wanted quickly instead of storing it.

What goes into the water decides where it can go. Soaps and detergents differ enormously in what they leave behind, and some are fine on a garden while others accumulate in soil and damage its structure. This is one to check on your own products, because what's sold varies by country.

Drainage proper is about keeping water away from what it shouldn't be in: foundations, tracks, stores and stock ground. Water moves downhill and finds any path you leave it, so the work is deciding the path before it decides for itself. Where sewage is involved, that's a separate subject with its own rules, and it doesn't mix with this one.

Where this connects

  • Health & Sanitation

    Most illness on a self-sufficient holding travels by water, so the treatment step here and the hygiene practice there are one subject in two places.

  • Sewage & Human Waste

    Blackwater is handled entirely apart from greywater, and keeping the two separate is the whole of the design.

  • Land Stewardship

    What the catchment above you does ends up in your water, which makes the state of the land an upstream water question.

  • Free Energy

    Falling water is both a supply problem and a power source, and the same head that gives you pressure can turn a wheel.

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Questions

How much water storage do I actually need?
Work it from your own daily use and your own longest dry run, not from a rule of thumb. Add up what the household draws in a day for drinking, cooking, washing, stock and any irrigation you refuse to lose, then multiply by the number of days you want to be able to go without useful rain. Annual rainfall averages are the wrong input, because the average hides the gap that catches you out.
Is rainwater safe to drink straight from the tank?
Not by default. It depends on the roof, the gutters, whether a first-flush diverter is fitted, whether the tank is sealed and screened, and how long it's been sitting. Rainwater starts clean and picks up everything between the sky and the tap. Treat it unless you have a good reason not to, and be more careful again with a roof whose coating you don't know.
What is the difference between greywater and blackwater?
Greywater is from washing, laundry and the kitchen. Blackwater is from toilets. They're handled completely differently, and mixing them turns an easy problem into a difficult one, because greywater can irrigate within hours while blackwater needs proper treatment before it goes anywhere.
Can I filter water instead of boiling it?
Sometimes, and it depends what you're removing. Fine filtration handles sediment and many organisms; what passes through varies with the pore size, and no filter deals with dissolved chemical contamination. Boiling is the most reliable single method available with no supplies at all, which is why it remains the fallback everywhere. Clear the water first either way: turbidity defeats filters and chemical treatment alike.
More questions, and every other subject, in the FAQ.

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