Avelar Home Inspection

Learning about plumbing

Plumbing can be defined as the practice, materials, and fixtures used in installing, maintaining, and altering pipes, fixtures, appliances, and have equipment in connection with waste/storm drainage facilities, a venting system, and public or private water supply systems.

As a home inspector, our primary concern while inspecting plumbing is to ensure a safe water supply system, an adequate drainage system, and ample and proper fixtures/equipment that do not contaminate the potable water. There are two primary reasons for a professionally designed plumbing system: 

  • To provide an adequate supply of potable hot and cold water to the occupants 
  • To supply means for wastewater and sewage to be discharged into the public or private disposal system.

Getting water to your home

If you live in an urban area, it is likely that the municipality is supplying water. Many homes and business in rural areas however, use drilled or dug wells to supply water to one or more dwellings. Both systems have service piping that goes to the home. 

Service piping will run from the water main, or the well pump. That piping should be as short as possible, with few elbows and bends to maintain water press; the line also needs to be protected from freezing, which means that we bury the service piping below the frost line (approximately 1.22m, variers by geographical location).

In modern urban areas, the service pipe should be ¾” and have about 40psi. Things you should not see on supply/service piping are:

  • Cement or concrete joints
  • Glue on joints between different types of plastic
  • No female threaded PVC fittings

Below is a representation of how water supplied to your home. 

The image is provided by InterNACHI©.

As you can see there are several shut offs on the way inside the home, these each have a reason for existing. The first is the “Corporation Stop” used when the home is being built, or for an emergency, for example if something happened the pipe between the corporation stop and the curb stop. The corporation stop is buried under the road and is difficult to get to.

The next is the curb stop, this is like the corporation valve, but easier to access and generally used because of nonpayment of water bills, or flooded basements.

The next is the meter stop. Well, it is two valves. When we have public water service, we are billed based on several factors including consumption. The meter is isolated by two valves, one on either side. This way you can turn off the water to the meter and the house, or just the house. It also allows for maintenance and replacement of the meter with minimal interruption to service.

Now, something to keep in mind, the meter stop valves can be ruined in a short time if used too often.

Getting hot and cold water to the faucet

Now that we have seen how the water gets into your home, let us see where it goes from there. Below is a diagram of what the water supply system generally looks like. 

The image is provided by InterNACHI©.

As you can see from the diagram, we have our hot water tank in the middle with a furnace coil and risers for the hot and cold risers. Pipes are usually hung from the basement or crawl space ceiling, they should be neatly installed, be supported by pipe hangers/strapping with enough strength to prevent sagging and to provide support in walls as risers should not depend on support from the mains. In centennial homes, there is a possibility that the copper pipping used lead solder. It is recommended that if
you live in a centennial home that you have your water tested, and if excess lead is present – act.

The hot and cold piping should be approximately 15.24cm (6”) apart, unless the hot water piping is insulated, this will prevent the cold piping from absorbing heat from the hot water pipe.

In certain situations, the supply mains in a home require repair or replacement and it requires draining the system, a drain/waste valve on the lower end of the line or on the end of each riser.

In homes without a basement, water lines are preferably found in the crawl space or under the slab. In some cases, they may be in the attic space; this arrangement can lead to problems due to freezing pipes, condensation, and leaky pipes. Having leaking pipes in your attic space will lead to some serious damage to the interior of the home.

Piping Material

In many homes you will see different types of piping material, let us go through some of the most common types here.

PVC or Polyvinyl Chloride: this type of plastic pipe is widely used in the construction industry in applications such as sprinkler systems; swimming pool pumping systems; low-pressure drain systems; water service between the meter and the building. It is exceptionally durable, however, has potential health hazards. [Read more from Nick Gromicko, CMI® in his article PVC Health Hazards]

CPVC or Chlorinated PVC: Unlike PVC, which is white in colour, CPVC is yellow in colour. It is durable, but not as tough as copper. It is a good choice for where supply water is corrosive as CPVC is designed for both hot and cold applications for potable water service.

Copper: One of the most recognizable material and durable material. Copper
should not be used in areas where the water pH is 6.5 or less. Unless a proper
water treatment system has been put into place. 
Copper has three grades:

    • M: which is a thin wall pipe used mainly inside of homes
    • L: which is a thicker wall pipe used mainly outside for water (hose bib)
    • K: which is the thickest use mainly for water mains and the water meter

Galvanized Steel: The typical life space of galvanized steel pipes is about 40 years, because galvanized steel corrodes easily these pipes will become restricted over time, until it is blocked. Here are some other problems with having galvanized steel piping if you mismatch the metals with brass or copper it will rapidly corrode. Often, copper piping is used by the electrical system to ground that system. When these different materials are introduced, the corrosion (simply put) becomes like an insulator and the home’s electrical system could become ungrounded.

PEX or polyethylene: Great choice for replacing old piping and for new builds. It is a resilient product that works well with corrosive water conditions and stretches
to accommodate freezing. This only makes PEX highly freeze-resistant – not freeze proof.

Kitec®: A type of brass plumbing fitting that was used from 1990 to 2005, it was recalled because the fittings would rapidly corrode leading to water damage.

Poly: mainly used for cold water, it comes in coils. They tend to crack as they age or wear from rocks. Often the stainless-steel clamps or galvanized couplings would corrode.

Polybutylene (PB, PB2110): PB was a plastic made between 1978 and 1995 and had many great advantages. Unfortunately, over time we discovered that this type of plastic had an adverse reaction with some of the water treatment chemicals which causes the plastic to flake and eventually burst.

Valves: When would I see or use them?

It is important that there be valves in a water system to allow it to be controlled in a safe manner. How many depend on how complicated the water system is. Let us look at some common valves you may or may not find in your home.

Shutoff Valves: these valves are used to allow servicing of parts of the plumbing system without having to drain the whole system. There are different types of valves (ball or gate) and locations [see image above].

Check Valves: Only let water flow in one direction.

Flow Control Valves: Used to supply a uniform flow at variable pressures, usually when there is a limited water supply.

Relief Valves: Used to release excess pressure from the plumbing system.

Pressure Reducing Valves: Used to reduce pressure in the pipes which allows us to use thinner piping in homes. Found on main lines.

Altitude Valves: sometimes found installed at the base of a hot water tank to prevent overflowing.

Foot Valves: installed inside a well at the end of the suction pipe or under the jet to prevent backflow and loss or prime. High quality valves are recommended.

Frost Proof Hose Bibs: Hose bibs installed on the exterior of the home that are frost-proof or freeze-resistant, have the valve inside the home and operating controls outside. [Diagram of Hose Bibb]

Frost Proof Hydrants: They work in the same way that the bibs work, except the shutoff valve is buried below the frost line to prevent freezing. However, due to the possibility of contaminating local water sources, these may be prohibited in your area.

Float Valves: You will generally see float valves inside of toilets and sump pumps. When the float is raised to the top, the valve will open or close depending on the configuration.

Different types of switches used: In plumbing, there are switches that are used to control flow and pressure some of them are: float, pressure, low-flow cut-off, high-pressure cut-off, paddle-type. All these switches are used to keep us safe, especially from cross-contamination of potable water.

Heating water

As people, we have various needs for hot water. We generally use hot water tanks to heat and store water for our use in our daily lives. Theses tanks use electricity, fuel oil, natural gases, and in some cases solid fuel like coal or wood. Hot water tanks come with a variety of safety features depending on the fuel type, but all should have what is called a temperature-pressure relieve (TPR) valve and should be in plain site; there should be a drip leg discharging no higher than 6” from the floor. If installed properly, the TPR will allow a safe way to let excess pressure to evacuate the tank. If this is happening, it is important to contact your plumber or rental company to inspect and possibly replace the hot water tank.

The image is provided by InterNACHI©.

Another method that is growing in popularity are tankless water heaters or on-demand water heaters. These types of heaters remove the tank and only heats the water when there is a call for it. They come in difference sizes and the proper make and model should be choose for your needs. They have a higher lifespan than convention tanks and are easier to repair.


When we use and consume water, it usually ends up in the drain. The drainage system or sanitary drainage system is used to carry only interior wastewater. The size of the sanitary drain depends on how many fixtures it’s servicing, usually it is no less than 4” in diameter. The requirements are different for different areas. Some of the materials you can see are waste plumbing made from cast iron, copper, vitrified clay, plastic, and in rare cases lead. The best choices today are PVC or ABS depending on your geographical area, here in Ottawa it is ABS.

To help protect us from sewer gases, we install a device called a plumbing trap. This trap creates a water-seal between the inlet of the waste plumbing and the open waste line to the sewer. Sewer gases are extremely harmful, and certain gases are explosive.

The P-Trap is the most common trap used (see above).

The is another important component that is part of the waste drainage system, the venting system. Without the venting system, drains would not work properly and would syphon the water seal out leading to sewer gases entering the home. Traps like the Full S-Trap, the ¾ S-Trap are rare to find, but in these cases proper venting is paramount. Proper venting helps prevent trap seal loss, material deterioration, and flow restriction.

Water Quality Problems

Understanding the proper maintenance procedures for preventing or reducing water quality problems we must understand how we figure out the chemical aggressiveness of the water. Earlier I mentioned that if the pH balance is too low, this would corrode copper piping. If the water is not balance, it will require extra care and equipment to have healthy drinking water.