Home Plumbing Basics: What Buyers and Homeowners Should Know
When touring a home, it's easy to focus on the kitchen, bathrooms, flooring, and finishes. But behind the walls and beneath the floors is a system that deserves just as much attention: the plumbing.
A beautiful home can have aging pipes, hidden leaks, or drainage problems that aren't obvious during a showing.
Understanding a few plumbing basics can help buyers ask better questions and homeowners recognize potential problems before they become expensive repairs.
Understanding Your Home's Plumbing System
Residential plumbing generally consists of three main parts:
Water supply: Brings clean water into the home and distributes it to faucets, showers, toilets, and appliances.
Drain, waste, and vent system: Carries wastewater out of the home and uses vent piping to help drains function properly.
Water heating: Supplies hot water to fixtures and appliances.
Homes connected to municipal water and sewer systems have different service arrangements than properties with private wells and septic systems.
The water supply and wastewater systems serve different purposes, and the materials used in each can be different.
Common Water Supply Pipe Materials
Not all homes have the same plumbing materials. Some older houses have even been updated in stages, leaving a mixture of original and newer piping.
Copper
Copper has been widely used for residential water supply piping for decades.
Advantages:
Durable when installed properly and used under suitable water conditions
Rigid and widely recognized
Does not rust like galvanized steel
Things to watch:
Pinholes or corrosion
Leaking soldered joints
Damage from freezing
Copper is generally a desirable material, but its condition matters more than its appearance alone.
PEX
PEX is flexible plastic tubing commonly used in modern residential plumbing.
Advantages:
Flexible and easier to route around framing
Requires fewer fittings in some installations
Does not corrode like metal piping
Things to watch:
Improper fittings or installation
Damage from sunlight exposure
Physical damage and manufacturer-specific installation requirements
PEX is common in new construction and remodeling. The quality of the installation is important.
CPVC
CPVC is a rigid plastic piping material used in some residential hot and cold water systems.
It can be suitable when properly installed, but older or improperly handled piping may become brittle. Its condition and the manufacturer's requirements should be considered before making modifications.
Galvanized Steel
Galvanized steel water pipes are commonly encountered in older homes.
Over time, corrosion and mineral buildup can reduce the inside diameter of the pipe.
Possible warning signs:
Reduced water flow
Discolored water
Corrosion around fittings
Leaks at threaded connections
Not every galvanized pipe is actively failing, but its presence deserves closer evaluation.
Lead Service Lines
Some older homes may still have lead water service lines connecting the property to the public water main.
Lead can also be associated with older plumbing fixtures, solder, and certain galvanized pipes.
The Michigan Department of Environment, Great Lakes, and Energy provides information about lead in drinking water.
If you're buying an older home, ask the water utility about the property's service line material. Water testing may also be appropriate.
Drain and Sewer Pipe Materials
Supply pipes bring water into the home. Drain pipes carry wastewater away.
Common drain materials include:
PVC: Common plastic drain piping used in many modern installations.
ABS: Another plastic drain material found in some residential systems.
Cast iron: Frequently encountered in older homes. It is heavy and can be relatively quiet, but aging pipes may develop corrosion, cracks, or deterioration.
Galvanized steel: Sometimes found in older interior drain systems and may become restricted by corrosion.
Clay and other older sewer materials: May be found in underground sewer laterals, depending on the home's age and location.
Remember that the pipes visible in the basement may not be the same material as the underground sewer line.
If the home uses a private septic system rather than municipal sewer, the inspection process is different. Read my guide to buying a home with a septic system in Michigan to understand what buyers should investigate.
Water Pressure vs. Water Flow
These terms are related, but they aren't the same thing.
Water pressure is the force pushing water through the plumbing.
Water flow is the volume of water delivered over time.
A home can have adequate pressure but disappointing flow because of restricted pipes, partially closed valves, clogged aerators, or other issues.
During a showing, try multiple fixtures and pay attention to noticeable changes when more than one fixture is running.
Low flow doesn't automatically mean the entire house needs to be repiped, but it deserves investigation.
Excessive water pressure can also damage fixtures, appliances, and plumbing components.
Know Where the Main Water Shutoff Is Located
One of the most important things every homeowner should know is how to shut off the water in an emergency.
In many Michigan homes, the main shutoff valve is located in the basement near where the water service enters the house.
Other locations are possible.
Homeowners should also identify individual shutoff valves serving toilets, sinks, and appliances.
A leaking washing machine hose or failed plumbing connection can cause substantial damage if water continues flowing.
If a valve is corroded, leaking, or difficult to operate, have it evaluated rather than forcing it.
Water Heaters: What Buyers Should Check
A home's water heater is another important plumbing component.
Common residential systems include:
Traditional storage tank water heaters
Tankless water heaters
Electric water heaters
Gas-fired water heaters
Heat pump water heaters
During a home purchase, consider the equipment's approximate age, condition, installation, capacity, venting where applicable, and maintenance history.
Look for visible corrosion, leaks, or unusual installation conditions.
Warning Signs of Plumbing Problems
Here are some things worth paying attention to during a showing or while maintaining your own home:
Water stains on ceilings or walls
Soft flooring around toilets, tubs, or showers
Musty odors near plumbing fixtures
Slow drains or recurring backups
Water hammer or unusual pipe noises
Corrosion or mineral deposits around fittings
Unexpected increases in water bills
A sump pump that runs frequently or behaves unusually
One warning sign doesn't necessarily indicate a major problem. Several together may justify additional investigation.
The EPA's WaterSense home maintenance guidance explains how homeowners can monitor for hidden leaks, including checking the water meter while no water is being used.
What a Home Inspection Can and Cannot Tell You
A general home inspection can provide useful information about accessible plumbing components and how fixtures function.
However, a typical inspection cannot reveal every concealed pipe, verify every connection inside a wall, or determine the full condition of an underground sewer lateral.
Depending on the property, buyers may want additional evaluations such as:
A licensed plumber's assessment
Sewer camera inspection
Water quality testing
Verification of water service line materials
Further investigation of suspected leaks or drainage issues
This is especially important when buying an older home or a property with signs of past water damage.
Does Older Plumbing Mean You Should Avoid the House?
Many older homes have plumbing systems that remain functional, and some have received significant upgrades over the years.
The important questions are:
What materials are present?
What has already been replaced?
Were the improvements completed properly?
Are there active problems?
What repairs or replacements may be needed in the future?
A home with some original plumbing isn't automatically a bad purchase.
However, buyers should understand the condition and potential costs before deciding what the property is worth to them.
Should Sellers Replace Plumbing Before Listing?
Not every older pipe needs to be replaced before selling.
A better approach is to identify active leaks, obvious defects, and known problems that could affect buyer confidence or financing.
If a significant issue is discovered, sellers can evaluate repair options, pricing, and disclosure obligations.
For some homes, making a targeted repair may be worthwhile. For others, the better decision may be to price the property appropriately and allow the buyer to plan future improvements.
This article is general educational information. Plumbing conditions and applicable codes vary. Consult a qualified licensed professional for property-specific evaluation and repairs.