What to Know About Home Plumbing

Basic of basic plumbing pipe materials and their safety and usage to prevent expensive water damage to a home and preserve the safety of your family.

Do You Know How Your Water Flows? 

Most homeowners take their plumbing for granted. They turn on the tap, the water flows. The shower sprays. The toilet flushes. Everything works. It’s fine.

Homeowners are often surprised by home inspection recommendations that suggest plumbing changes when everything seems fine. You may get recommendations like these:

 Monitor, Repair:  Evidence of standing water was noted at the basement/sub-area crawl space. It is recommended a licensed drainage expert be consulted to obtain further information on this condition (the crawlspace was not fully accessible as a result of this condition). 

  • Repair:  A non-conforming PVC plastic plumbing installation was noted (PVC pipe not approved for use inside footprint of structure).
  • Repair:  Leaking water supply line(s) were noted at the master bathroom sink faucet.
  • Repair:  Rusting (pinholed) and leaking galvanized steel supply plumbing was noted at the garage (near water heater). It is recommended a licensed plumbing contractor be contacted to further investigate this condition.
  • Monitor:   Oxidation and corrosion was noted at galvanized steel plumbing at the sub-area crawlspace under the kitchen. No leaking was noted at the time of the inspection.

The reason is, as your inspector pokes around they’ll notice old or worn plumbing that could leak or burst due to rust accumulation or faulty materials. And, although this rarely happens now, hazardous exposure from long-lasting but toxic lead pipes. 

You may think a home inspection is just an annoying part of real estate transactions, but it’s much, much more. Your home inspector turns his professional eye on the systems in your home with an eye toward structural soundness and safety. 

So when your home inspector makes a recommendation, it’s all about the safety and soundness of the home. For example, replacing old, rusted pipes with a potential to burst with sound copper plumbing can prevent water damage that can run into the tens of thousands of dollars, not to mention the massive inconvenience.

Water damage can result in floor and wall replacement requiring gutting and eventual new flooring. Plus, new walls, wall coverings, cabinets, drawers, and, of course, new plumbing.

Different Types of Pipes to Carry Water in Your Home

The material of your water pipes can vary with the year your house was built and any plumbing retrofits or upgrades. Pipe material varies in flexibility, durability, and deterioration rates. Choosing the right pipe for your plumbing depends on a number of factors including local building code regulations. Consult with a licensed plumber to seek advice about your choice.

Plastic Piping Options

Plastics are long-lasting and easy to install or replace. Plastic piping options are cheaper than metal, easier to work with, and highly resistant to corrosion. However, the choice of materials will depend on whether a portion of the old line is to remain intact. For example, a contractor will not want to splice a PVC line between two cast iron lines.

Polyvinyl chloride (PVC)

PVC is commonly used for main supply lines, drainage pipes, pools, spas, and irrigation piping. Normally it is used for conducting cold water because hot water can break it down over time. Also, especially when used outside, PVC can degrade from heat and ultraviolet (UV) rays from sunlight. It is also a relatively inexpensive material for installation and easy to repair or replace.

PVC is a great option for:

  • Sink, toilet, and bathtub drain lines
  • Vent stacks
  • Main water supply line
  • High-pressure applications

Acrylonitrile butadiene styrene (ABS) 

ABS is a black plastic pipe similar to PVC but more prone to deterioration. It was once commonly used in home plumbing. It is easy to install, strong, and holds up well underground. If you live in an older home with ABS, check for warping from sun exposure and loosened joints. 

Cross-linked polyethylene (PEX) 

PEX is highly flexible and suitable for both hot and cold water supply lines. It can curve around corners and obstructions requiring fewer connections. Flexibility includes the ability to expand and contract making the pipe highly freeze resistant. Although it can withstand high temperatures, it can’t be connected directly to a water heater. Use copper piping or another hot-water piping for the connection.

PEX is a good option for:

  • Repiping and retrofitting
  • Snaking through walls and small spaces


If your home was constructed between the late ‘70s and early ‘90s, it might have polybutylene pipes. Polybutylene is no longer used because of its tendency to leak and burst.  Once considered an inexpensive plumbing solution, polybutylene piping is prone to burst resulting in flooding and extensive water damage. If your home inspector finds polybutylene pipes you’ll want to replace them to avoid costly damage. 

Metal Piping Options

Metal pipes are used for their strength, toughness, and durability. Metal piping options are more expensive than plastic but generally, last longer than plastic. 


Copper pipes are heat and corrosion resistant and they have natural anti-microbial properties. Use copper both above and below ground. Although the materials and labor installation are more expensive than plastic, copper lasts a good 50 years before it begins to thin. Some soils can erode copper, so use sleeves for installation below ground. 

Cast Iron

Before 1960, cast iron pipes were the main choice for drain lines. They are extremely durable, heat resistant, and good for sound reduction, but they tend to rust over time. If your cast iron pipes show signs of rust, use PVC or ABS pipes to replace the rusted sections.


Lead pipes were common in homes until the 1950s. Lead is strong and durable, but it poisons the water. Heavy metal poisoning can lead to irreversible kidney and nervous system damage. If you have an older property, check that all lead piping has been replaced.

Galvanized Steel or Iron 

These pipes have been coated with zinc to prevent corrosion. Safe for conducting water these pipes eventually corrode and begin to leak. Replace them with copper, PVC, or PEX. Galvanized pipes are rarely used in modern home construction. 

Professional Assessment for Home Inspection Recommendations

Your home inspector bases recommendations on findings of the condition of your plumbing at the time of the inspection. Consult with a licensed, professional plumbing contractor to determine the best solution for retrofitting or repairs. They will determine the right plumbing materials and fittings for your home. 

A professional home inspection can save you thousands of dollars in potential damage as a result of old and weakened plumbing. Use Inspect.com to find the perfect home inspector in your area.

Published in the American Society of Home Inspectors ASHI Reporter, January 2021 issue.


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