Where Your Water Comes From

The Plumbing Series, Lesson 1 · Taught by Professor Elias Walls · Researched and reviewed by Grant Doutt, Certified Master Inspector®

🎓 The Professor's Quick Answer

Your water reaches the kitchen faucet through a short chain of hardware, and almost nobody can name the links. In order, they are: the source (a city water main or your own well), a service line running to your property, a meter, a main shutoff valve, and, in most homes, a pressure regulator.

Three things in that chain decide whether your plumbing lasts or fails early:

• The main shutoff valve. If you cannot find it, or it will not close, a burst pipe becomes a flood.

• Water pressure. The healthy range for a home is roughly 40 to 60 psi. Above 80 psi is considered excessive, and it wears out every faucet, valve, hose and water heater in the house.

• The pressure regulator. It keeps the pressure inside that safe range, and it wears out too.

If you are on a private well, there is one more fact that matters: nobody tests that water for you. In Florida, that job belongs to the homeowner.

🏫 Welcome Back to the Knowledge Center

Class, we have spent our time on the parts of a house you can see from the street: the walls, the roof, the air conditioner, the wiring. Today we begin a new series on the system hidden inside all of them, the one that moves water.

Plumbing is really two systems, and we will teach them in two halves. The first half is delivery: how clean, pressurized water gets into the house and to every fixture. The second half is evacuation: how the used water leaves. Today is Lesson 1 of the delivery half, and we start where the water starts.

🏘️ Before There Was a Pipe at the Street

For most of history, every house was its own water company. You had a well, a cistern or a nearby spring, and you carried the water in. Nothing was piped to the house.

City water systems changed that. A utility draws the water, treats it, pressurizes it, and sends it through large pipes under the street. Your house connects to that network with a single branch, which is why a failure at the front of the house matters so much. Everything downstream depends on it.

One point surprises people. In Florida, groundwater is the primary source of both public and private drinking water. The big difference between a city system and a well is not usually where the water originates. It is who is responsible for treating, testing and maintaining everything between the ground and your glass.

🏙️ City Water: The Journey From the Street to Your Kitchen

If your home is on a municipal or county utility, here is the path the water takes, from the street inward.

The main. The large pipe under the street, owned and maintained by the utility.

The service line. A smaller pipe branches off the main and runs to your property. It is buried, out of sight, and it is the least-inspected pipe in the whole system.

The meter. Near the property line you will usually find a ground-level box with a lid, often labeled "WATER." Inside is the meter, which measures what you use. Many homes have two valves at this point: one on the street side of the meter, which belongs to the utility, and one on the house side, which is generally the homeowner's.

A possible one-way valve. Many utilities install a check valve or backflow preventer at or near the meter. It stops water from flowing backward into the public supply if pressure drops in the main during a hydrant draw or a main break.

Your house. The line crosses your yard, comes up through the slab or foundation, and passes the main shutoff valve we will get to shortly.

A rule of thumb on responsibility: the meter and the street-side valve are the utility's, and the house-side valve and everything beyond it are the homeowner's. Utilities differ on exactly where their ownership ends, so if you suspect a leak between the meter and the house, call the utility first and ask which side it is on before you pay anyone.

🗼 Why Your City Has Water Towers

Every town has at least one: a tall tank on a leg or a pedestal, usually with the town's name painted on it. It is the biggest piece of your water system, and it explains a lot about the pressure inside your house.

It uses gravity as a pump. Water stored high above town pushes down on the water below it, the same way pressure builds as you dive deeper in a pool. Every foot of height adds roughly 0.43 psi, so a tank 100 feet up adds about 43 psi. That is why the tank sits well above the homes it serves.

It lets the utility use smaller pumps. Demand is not steady. Morning showers and evening dishes drive big spikes, while at 3 a.m. almost nobody is using water. Without a tower, the pumps would be sized for the worst hour of the day and sit mostly idle the rest. With one, smaller pumps run steadily, filling the tank overnight and during the midday lull, and the tank covers the rush. Peak hourly demand can run about five times the average. Running the pumps overnight, when electricity is cheaper, saves money too.

It holds a reserve. Firefighting needs a huge, sudden amount of water, and the tank is ready for it. If the power goes out and the pumps stop, the tank can keep the system under pressure, in some cases for a day or more.

What it means for your house. Your pressure depends partly on where you live. Homes at lower ground or close to the tower see higher pressure than homes on high ground or far away, and a house at the bottom of the system can see far more than its plumbing was built for. Pressure also moves through the day: higher when the tank is full, lower at the morning rush. That is why one reading at one hour is not the whole story.

Not every community uses a tower. Some systems use ground-level tanks with pumps, and your utility can tell you which yours does.

🕳️ Well Water: When You're the Water Company

Many Florida homes, especially on larger lots and in rural areas, are on private wells. A well changes the arrangement in a few important ways.

There is a pump and a pressure tank. A well pump draws water from the ground into a pressure tank, which holds a cushion of compressed air and water so the pump does not run every time you open a tap. The pump starts when pressure falls to a set level and stops when it rises to another. That cycle is where your home's pressure comes from.

Nobody is testing it for you. Public water systems in Florida must run routine tests to meet state standards. Private well owners are responsible for their own water. The Florida Department of Health recommends testing at least once a year for bacteria and nitrate, and UF's extension service adds lead and pH. A state-certified laboratory should do the testing.

Nothing makes anyone test it when the house sells. Florida has no requirement for well sampling at sale, or for routine sampling of private wells. If a house you are buying has a well, the test is your decision, and it is one of the cheapest forms of insurance you can buy.

A well can be a public water system. In Florida, a well that serves two or more rental residences, or a day care, group home, nursing home or assisted living facility, is a public water system and not a private well. That changes who regulates it.

Quality changes over time. The health department calls out the myth that "nobody has gotten sick, so it must be safe." A clean test when the well was drilled says little about the water today, and a change in color, taste or odor is a reason to test immediately.

🚰 The Main Shutoff: The Most Important Valve in Your House

Class, if you remember one thing from today, make it this. Somewhere on the pipe that enters your home is a valve that stops all the water. When a supply line bursts or a water heater fails, that valve is the difference between a mop and a mitigation company.

Where to find it. It sits on the incoming line close to where it enters the house, before the line branches to the fixtures. In many slab-on-grade homes, a common construction style in Florida, the line often enters through the garage, so look there first: the wall nearest the street, near the water heater, or near a utility sink. You can also trace the cold-water line into the water heater backward. In some homes it is outside near the meter or on an exterior wall.

Gate valves and ball valves. Know which one you have.

• A gate valve has a round, wheel-style handle that takes many turns to open or close. It is the older style.

• A ball valve has a lever handle. A quarter turn opens or closes it: lined up with the pipe is open, crosswise is closed. It is the modern standard.

Both close clockwise.

The old gate valve problem. Gate valves that have not moved in years tend to seize or stop sealing. A fouled one may slow the water but not stop it, and "most of the way" is not good enough when a pipe is leaking. A worn one can also break when someone finally forces it. Plumbers replace failing main valves with full-port ball valves, and the part itself is inexpensive.

Test it before you need it. Once or twice a year, close the main gently, confirm the water stops at a faucet, and open it again. If it will not turn, only half-closes, or weeps around the handle, have a plumber replace it on your schedule and not in the middle of a flood. Then tag the valve so anyone in the house can find it.

💪 Pressure: The Number Nobody Checks

Water pressure is measured in pounds per square inch, or psi. It decides how hard water pushes on everything it touches.

• 40 to 60 psi is the range most people consider healthy for a home.

• 80 psi is the generally accepted maximum. Plumbing codes in most places limit static pressure inside a house to 80 psi and require a regulator when the supply is higher.

• 20 psi is the minimum for fixtures to work under code, though anything under 40 feels weak in the shower.

Why high pressure is a problem. Pressure above 80 psi shortens the life of everything it touches: supply lines, water heaters, faucet cartridges, toilet fill valves and appliance hoses. It also makes water hammer worse, the banging in the walls when a valve shuts quickly. Think of it as high blood pressure for the house.

Signs it may be too high: knocking pipes when a faucet or appliance shuts off, a dripping water heater relief valve, and faucets, fill valves and washing-machine hoses that fail again and again.

Signs it may be too low: weak flow at every fixture points to the regulator, the main valve or the supply. Weak flow at just one fixture is usually a clogged screen or cartridge. A big drop when two things run at once can mean undersized or corroded pipes, which is Lesson 2.

How to check. A pressure gauge screws onto an outdoor hose spigot and costs very little. Read it with no water running, and use a spigot downstream of the regulator, since that is the pressure your plumbing actually sees. Do not rely on a single reading, and remember cheap gauges are not precise. A reading that stays around 80 psi or higher is worth taking seriously.

🔧 The Pressure Regulator

If the pressure coming in is too high, the part that fixes it is the pressure reducing valve, usually called the PRV or regulator. It is typically a bell-shaped brass valve on the main line, after the meter and main shutoff and before any branch lines. Inside, a spring and a rubber seal hold the pressure at a preset level no matter how much water you use. It can be adjusted with a screw, and plumbers commonly aim for about 50 to 60 psi.

It wears out. One California regulator program reports that private pressure reducing valves last around ten years, and its testing found many that were not working at all. Springs weaken, diaphragms crack, and screens clog.

It can fail two ways. Stuck open, it stops reducing, and your house sees full street pressure, sometimes over 100 psi, with no warning until fixtures start failing. Stuck closed, the flow drops to a trickle.

The utility's regulator is not yours. In some areas the utility installs one at the meter to protect the meter, not your plumbing. If your house has no regulator of its own and the street pressure is high, that is a gap worth closing, and a plumber should evaluate any home that measures above 80 psi.

There is one more part tied to the regulator, a small tank near the water heater. It belongs in the lesson on how water gets heated, so we will cover it there in Lesson 3.

🔍 What We Check During the Inspection

An inspection reads what can be seen and tested without taking anything apart.

• The source. City or well, and where the system enters the house.

• The main shutoff. Whether we can find it, what type it is, and its condition. A stuck or leaking old gate valve gets written up.

• The regulator. Whether there is one, how old it looks, and whether it is leaking or corroded.

• Pressure. Signs of high or low pressure at the fixtures we operate, and any water hammer.

• Well systems. The pump, pressure tank and wellhead as far as they are visible. We cannot see inside the well, which is why we recommend a certified lab test.

We do not replace valves, regulators or pipes, and we do not sell repairs. Our job is to tell you what we see so you can decide what to do with a licensed plumber.

❓ Questions From the Back Row

Is city water safer than well water?

Public systems must test routinely and meet state standards. Well water can be excellent, but the owner is responsible for knowing that, and the Department of Health notes that quality changes over time.

What happens to my water if the power goes out?

On city water, the tower or storage tank can keep the system pressurized for a time after the pumps stop, so you often still have water. That is not guaranteed in a long outage, and a storm can break lines too. A private well pump needs electricity, so no power usually means no water unless you have a generator.

My main shutoff is an old wheel-handle valve. Should I replace it?

If it turns fully and stops the water completely, it is doing its job. If it is stiff, leaks around the handle, or does not fully close, replace it before the flood shows you.

Do I need a pressure gauge?

You do not need one, but a hose-spigot gauge is one of the cheapest and most useful things a homeowner can own. Check it once, record the number, and check again after any plumbing work.

🚌 Field Trip

Your homework is a ten-minute walk.

1. Find the main shutoff. Garage first, then the exterior wall nearest the street. Note whether it is a wheel-handle gate valve or a lever-handle ball valve.

2. Test it. Turn it off gently, check that a faucet stops, turn it back on, and hang a tag on it.

3. Find the meter. With every faucet and appliance off, it should hold still. A moving dial or spinning low-flow indicator can mean a leak.

4. Check the pressure. Screw a gauge on an outdoor spigot, with no water running, and write down the number.

5. Look for the regulator. Find the bell-shaped brass valve on the main line.

That is your delivery system. The water you just traced goes next into pipes inside the walls, and the type of pipe your house was built with says a lot about its future. Lesson 2 is about those pipes: galvanized steel, copper, the infamous polybutylene, CPVC and PEX, and how each one fails.

Class dismissed.

Sources: Florida Department of Health, Private Well Testing guidance; University of Florida IFAS Extension, "Household Drinking Water Testing for Public and Private Water Supplies" (EDIS SS712); model plumbing code provisions on static pressure (80 psi) and pressure regulators; plumbing trade and municipal utility guidance on pressure reducing valves and main shutoff valves; Practical Engineering, "How Water Towers Work"; Mental Floss, "How Do Water Towers Work?" Utility ownership boundaries and local requirements vary. Any specific house should be evaluated on its own condition.

Thinking about a home inspection? Call (352) 272-1322 or visit fourcornershomeinspections.com.

Taught by Professor Elias Walls · Researched and reviewed by Grant Doutt, Certified Master Inspector® · Last reviewed: October 2026. Professor Elias Walls is the teaching persona of the Four Corners Knowledge Center. Every lesson is researched, written, and fact-checked by the licensed, certified inspectors of Four Corners Inspection Services.