Remodels By Leo – Trusted Bathroom Remodeling Experts in Atlanta
As a homeowner, you don’t need to be a licensed plumber—but knowing how your home’s plumbing system works can make a world of difference when it comes to repairs, remodels, or emergencies.
This guide breaks down the basics of residential water supply, drainage systems, and bathroom fixture plumbing so you can better understand what’s behind your walls—and what to do when things go wrong.
Whether you’re planning a remodel or just want to be more informed, here’s what you need to know.
🛠️ Residential Plumbing 101: What Every Homeowner Should Know
Written by Remodels By Leo — Bathroom Remodeling Experts in Atlanta
Residential plumbing is made up of two main systems: water supply and drain-waste-vent (DWV). Within those systems are a variety of pipe types and components that most modern homes share.
If you’re a homeowner, it’s smart to be at least somewhat familiar with how these systems work. This knowledge helps you make better decisions when it comes to maintenance, upgrades, or remodeling—and it can make a major difference during a plumbing emergency.
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💧 Understanding Your Home’s Water Supply
Most homes in the U.S., especially in metro areas, get their water from a municipal main line that runs under the street. These large-diameter pipes deliver high pressure and volume to each neighborhood.
When the line branches off to serve an individual home, the pipe diameter is typically reduced to about 1 inch. At that point, it’s connected to two critical components:
• A main shut-off valve
• A water meter
These are usually located just a few feet from the curb, on your property, and are often housed in a small underground box with a metal oval lid.
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🔍 Why You Should Know Where Your Water Meter Is
This little box might not look like much—but in the event of a leak or burst pipe, it becomes crucial. You should locate your water meter box today and make sure it’s not buried under soil, mulch, or other debris. Being able to access the main shut-off valve quickly can prevent serious water damage.
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💡 Emergency Tip: Open Your Faucets!
Whether you shut off the valve before or after spotting a leak, remember to open multiple faucets in the house right away. This relieves pressure in the lines and may help slow or stop water from leaking into the home.
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🧰 Pro Tip: Keep a Water Shut-Off Tool Handy
Many shut-off valves can be difficult (or impossible) to turn by hand—especially if they haven’t been used in years. That’s why we recommend investing in a water shut-off tool (usually around $12–$15 at Home Depot). Keep it in your garage or utility room for quick access. You don’t want to be hunting for it when time is critical.
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🧵 How Water Travels From the Street to Inside Your Home
Once the municipal water supply passes through the main shut-off valve and water meter, it flows underground through your yard and enters your home—typically at ground level or in a basement, if your house has one.
This section of pipe between the meter and your home is often called “the main.” If this pipe develops a leak, you’ll usually notice it as a wet or soggy patch in your yard, especially near the curb.
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🛠 Repairing or Replacing the Main Line
If you spot a leak in the main, the first step is to shut off the water at the meter and relieve pressure by opening faucets in your home. At that point, a plumber or contractor can assess whether the pipe needs a repair or full replacement.
• Main line replacements can cost several thousand dollars depending on length, depth, and material.
• However, a spot repair can often be done if the rest of the line is in good shape—and at a fraction of the cost.
A qualified contractor should be able to handle a standard main line repair in 1–2 hours without tearing up your entire yard. Stay alert: some companies overcharge for full replacements when a repair would do the job.
✅ Pro Tip: Always get a second opinion before approving a full main replacement.
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💥 Managing High Water Pressure: The Role of the PRV
When water enters your house from the street, it’s still under high pressure—often 100 PSI or more. That’s far too strong for home plumbing, so the line is routed through a Pressure Reducing Valve (PRV).
The PRV reduces the incoming pressure to a safe, usable range, typically between 50–70 PSI for residential homes.
Many newer PRVs include a built-in pressure gauge, which makes monitoring and adjustments much easier for both professionals and handy homeowners.
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🚰 The PRV Area: A Second Shut-Off Valve You Should Know About
In many homes, the location of the Pressure Reducing Valve (PRV) will also have a secondary shut-off valve—usually installed just before the PRV on the incoming line. This shut-off controls water entering the house from the main and can be critical in certain emergencies.
If a leak occurs inside the home, this PRV-area shut-off valve can quickly stop the flow of water before it reaches any fixtures. But if the leak is outside, in the underground main supply line (between the water meter and the house), this valve won’t help—because the break is before this shut-off. In that case, you’ll need to shut the water off at the meter.
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🧠 Know both shut-off locations:
• The main shut-off at the water meter (for leaks outside)
• The PRV-area shut-off inside the house (for leaks inside)
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📏 Pipe Sizes: How Water Is Routed Inside Your Home
After passing through the PRV, the water line is typically reduced to a ¾” pipe. From here, it branches in two directions:
• One line runs to your water heater, which becomes the hot water supply
• The other continues as the cold water supply throughout your home
As the water lines reach specific fixtures—such as faucets, toilets, washing machines, or outdoor spigots—the pipe size is further reduced to ½ inch, which is the standard supply size for most household fixtures. The cold side is always on the right and the hot side is always on the left.
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🔧 Common Pipe Materials in Residential Plumbing
Most modern homes today use one or more of the following pipe materials:
• Copper – durable, traditional, but more expensive
• PEX – flexible, easy to install, and affordable
• CPVC – rigid plastic, resistant to corrosion, but brittle over time
Each fixture is also required—by code—to have its own local shut-off valve (also called an angle stop). This lets you isolate and repair individual fixtures (like a leaking toilet or kitchen faucet) without having to shut off water to the entire house.
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🚿 Vanity Plumbing: What Homeowners Should Know
When it comes to bathroom vanity plumbing, there are a few consistent standards you’ll find in most homes. Understanding the layout can help you identify issues and communicate better with your plumber or contractor.
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🧱 Standard Vanity Plumbing Layout
• Drain Pipe:
The drain pipe exiting the wall is typically a 1.5-inch PVC (schedule 40). Occasionally, you may see ABS pipe used instead, though ABS is rare in Georgia residential construction.
• Drain Height:
The center of the drain outlet is usually installed 18 inches above the finished floor.
• Water Supply Lines:
• Cold water (right side) and hot water (left side) pipes are typically positioned 21 inches off the floor, just above the drain line.
• These lines are each connected to angle stop valves, which control the flow to the faucet.
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🚨 Watch Out for Aging Shut-Off Valves
Each supply line should have a shut-off valve (also called an angle stop) that allows you to isolate the fixture. This is useful if a faucet starts leaking or needs to be replaced.
However, older valves often corrode internally and may start leaking at the stem when turned. So if you ever shut off water to a vanity faucet:
• Double-check the valve stem after closing it
• Look for drips from the knob or stem area
• Be ready to replace the valve if it’s leaking
A small leak at the valve can go unnoticed and cause damage inside your vanity cabinet.
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💡 Faucet Style Tip: Upgrade to a Wider Spread
At Remodels By Leo, we typically install 3-piece faucets (also known as 8-inch spread faucets) on vanities. In our opinion, these offer a more refined, high-end look compared to single-handle units.
However, when possible, we recommend pre-drilling for a 10- or even 12-inch spread—if your vanity top allows for it. This provides:
• More spacing between the handles and spout
• Easier cleaning
• A more elegant, customized appearance
It’s a small design detail that makes a big difference.
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🛠️ Recap – Vanity Plumbing Basics:
• Drain: 1.5” PVC, 18” from floor
• Supply: Hot (left) & Cold (right) at 21” height
• Shut-off valves should be checked for stem leaks
• Consider wider faucet spreads for aesthetics and comfort
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🚽 Toilet (Commode) Plumbing: Simple but Essential
Toilet plumbing is one of the simpler setups in residential bathrooms, but it’s still important to understand how it functions.
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🧊 Water Supply Line
Toilets are supplied by a cold water line—typically ½ inch in diameter—that exits the wall (or sometimes the floor, especially on exterior walls). This line includes:
• A shut-off valve (angle stop)
• A flexible supply hose that connects the valve to the toilet tank
The supply line always exits on the left side of the toilet (as you face it) and sits roughly 5 to 6 inches above the finished floor.
This shut-off valve is what you’ll use to stop water flow when:
• Replacing the fill valve, flapper, or flush valve
• Installing or removing the toilet
• Addressing leaks or overflows
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💡 Adding an Electric Bidet
If you’re upgrading to an electric bidet seat, you’ll need more than just water—you’ll also need power.
🛠 Best practice:
• Install a GFCI outlet (and ideally also an AFCI) behind the toilet
• Place the outlet on the right-hand side (opposite the water supply)
• Raise it 10–12 inches above the floor to minimize water exposure in case of a leak
This layout keeps electrical components safe and convenient, and it complies with modern code and safety standards.
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🚿 Shower or Tub Valve Plumbing: What’s Behind the Wall
Shower and tub plumbing can vary in complexity depending on the fixtures and features involved, but it all starts with the valve body.
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🧰 Shower Valve Basics
• The valve body is a solid brass or copper fixture roughed into the wall during construction or remodel.
• It is secured to the framing for stability and receives:
• Cold water on the right
• Hot water on the left
From there:
• The bottom port of the valve connects to the tub spout (if present)
• The top port goes up to the shower head
If your setup includes only a shower (no tub), the bottom port is often capped.
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🔀 Diverters & Multi-Function Valves
For more advanced setups (e.g., handheld wands, body jets, rain heads), a diverter valve is often installed:
• The diverter connects to the top outlet of the main valve
• From the diverter, water is redirected to multiple outlets based on your preferred flow (shower head, wand, jets, etc.)
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🔧 What Controls the Water?
Connected to the valve body is the valve stem (or cartridge)—this is the part you turn to adjust temperature and flow. It’s usually plastic with rubber O-rings, and it regulates:
• The mix of hot and cold water
• The volume of flow
• The direction (to head, tub, wand, etc.), if integrated
Over time, these cartridges can wear out. You might notice:
• Water is too hot or cold
• Flow is uneven
• Dripping from the valve when shut off
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✅ The Good News
Modern valves from brands like Delta, Kohler, Hansgrohe, and others are designed with replaceable cartridges. That means:
• You don’t need to rip out tile or walls to fix temperature or pressure issues
• The brass valve body typically stays intact
• Replacing the valve stem is fast, clean, and cost-effective
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🏁 Final Thoughts
Understanding your home’s plumbing system—from the shut-off valve by the meter to the fittings behind your vanity—gives you a serious advantage as a homeowner. It helps you spot problems early, make better remodeling decisions, and avoid getting taken advantage of by unqualified contractors.
At Remodels By Leo, we specialize in bathroom remodels that go beyond surface-level beauty. We make sure everything behind the tile is just as solid as what you see on the outside—because lasting quality starts with great plumbing.
📞 Need help with your next remodel or plumbing upgrade?
Contact us today for a consultation and discover why so many Atlanta homeowners trust Remodels By Leo.
Thank you.
