Five places water comes from
A homestead can get water from five main sources:
- Municipal water: piped from a public water system run by a town or utility.
- Well: a hole drilled or dug down to groundwater, the water held in soil and rock underground. The water-bearing layer is called an aquifer.
- Spring: a place where groundwater comes to the surface on its own.
- Surface water: streams, rivers, ponds and lakes.
- Rainwater: water caught from a roof and stored.
Text description
A conceptual cross-section of a homestead, not to scale. On the left, a hill rises. Underground, the water table slopes down from under the hill. Below it, groundwater fills the gaps in soil and rock, called the aquifer, and solid rock lies deeper still. Where the water table meets the hillside, a spring comes out on its own and runs down to a stream at the foot of the hill, which is surface water. In the middle, rain falls on a house roof and runs into a storage tank beside the house. To the right, a well reaches down from the surface into the groundwater. At the far right, a municipal water main runs under a road, available only where public pipes reach.
Many homesteads use more than one. A common mix is a well for the house and rain for the garden.
Who is responsible for quality
This is the biggest difference between sources.
A public water system is regulated. It must treat and test its water and report the results to you each year.
A private water supply is not. The EPA and CDC are clear on this: if you own a private well, spring or rain system, you are responsible for keeping the water safe. No one tests it unless you do.
Text description
Two rows compared. Top row, a public water system, which is regulated: water goes from the town or utility, is treated and tested by the utility as the law requires, and reaches your tap, with results reported to you each year. Bottom row, a private supply, which is your responsibility: water goes from your own well, spring or rain system, is tested only if you do it, at least once a year with a state-certified lab, and reaches your tap. A note on the tap says that water looking fine is not proof that it is safe.
Water can look, smell and taste fine and still carry germs or chemicals. Bacteria, nitrate, arsenic and others give no warning. Testing is the only way to know.
Wells
About 40 to 43 million Americans, roughly one in eight to one in seven, get drinking water from a private well. The estimates differ by source and year (EPA, CDC, USGS).
A well can be very reliable. Groundwater is often steady through droughts, though not always. But a well is a large, uncertain cost. Depth, rock type and water quality vary a lot, even between neighbors. Drilling, a pump, pipe and wiring together can run from several thousand to tens of thousands of dollars. Local quotes are the only real number.
Ask neighbors and the county or state well records office how deep nearby wells go and how much water they give. That is free and very useful.
Springs, surface water and rain
Springs can give steady water with no pump if they sit uphill of the house. But flow can drop in dry years. Water near the surface can also pick up germs from animals and runoff.
Surface water is easy to see and often plentiful. It is also the most likely to carry germs, and it changes with every storm. It is usually treated before drinking, and many places restrict who can take it.
Rainwater is soft and starts fairly clean. But the roof, gutters and tank add dirt, bird droppings and leaves. Supply rises and falls with the seasons (lesson 16).
Sources side by side
Match the clue to the source
Which source does each statement describe best?
- Neighbors’ records help you guess the depth
- It is very soft, with few dissolved minerals
- It turns muddy after a storm upstream
- Animals upstream can add germs at any time
- Its cost is hard to know until the drilling is done
- Supply depends on roof size and monthly rainfall
Testing a private supply
The CDC and EPA advise testing a private well at least once a year. A yearly test usually covers total coliform bacteria, a sign that germs may be getting in. It also covers nitrate, pH and total dissolved solids.
Test again if the water changes in taste, smell or look, after a flood, or after work on the well. Your local health department can tell you what else to test for where you live. Arsenic, radon and uranium are common in some regions.
Use a lab certified by your state. Lesson 18 covers what to do with the results.
Pro and permit
Check
Your new well water is clear and tastes good. What should you do before relying on it for drinking?
Summary
- Five sources: municipal, well, spring, surface water and rain. Many homesteads mix two.
- Public water is tested for you. A private supply is your responsibility.
- Wells are often reliable but have a high, uncertain cost. Surface water has the highest germ risk.
- Test private water at least yearly with a state-certified lab, and check water rights first.
Next, you will work out how much rain a roof can catch.
Go deeper: why groundwater is not always safe
Soil filters out many germs as water soaks down, so deep groundwater is often cleaner than surface water. But shallow wells, cracked casings and nearby septic systems can let germs in. Some contaminants, such as arsenic and uranium, come from the rock itself. Others, like nitrate, come from fertilizer and manure. The USGS and state geological surveys publish maps of regional groundwater quality. They help you know what to test for, but they are not a test of your well.