Plumbing 101: Homeowner Plumbing Overview

While it’s often necessary to call a professional plumber to take care of any major plumbing problems in your home, understanding how your home plumbing system works can help you stay on top of maintenance and prevent any major problems or emergencies. Here are a few things everyone should know about their home’s plumbing system.

1. How water enters your home

home-plubming-diagramEvery residential plumbing system includes two subsystems: one to bring fresh water in, and one to take wastewater out. The water coming into the home (potable water) – either from your well or from your public utility company (water purveyor) – is called the water supply. If you use a public utility company, as water enters your home it passes through a meter which calculates how much water you are using, allowing the utility company to accurately calculate your water usage for billing purposes.

2. How you get cold and hot water

Water from the main supply is cold, so it is transported directly to the fixtures and appliances. To create hot water, a pipe carries water to your water heater (often located in a basement, utility room or closet). Then, a hot water line transports the hot water to all the fixtures and appliances that need hot water.

3. How to turn off your water

One of the most important things to be aware of as a homeowner is how to shut off your water. This can help prevent extensive damage to your home in the event of a water-related emergency (such as a burst pipe). To turn off water in your home, you must locate the valve and ensure it’s working well. If the valves haven’t been used in a long time, you may need to call a plumber to replace them. Valves that aren’t used or exercised regularly can seize up and no longer allow the valve to be turned into the off position, or leak when the handle is turned.

Start by ensuring you know how to turn off the water to the entire house at the main shut-off valve. This valve is often located in the basement or mechanical room of your home, near the meter if you have one or by where the plumbing enters your home. If you have concerns about the condition of your home shut off valve, or can’t find it, contact your local plumber. This main valve will shut off all hot and cold water in the home. If you determine that it is just a hot water issue, the valve just above your water heater will shut off all hot water only within the home. 

You can also turn off the water supply for each individual fixture (such as your sink faucet, toilet or washing machine). Each fixture should have its own dedicated supply valve nearby. For example, under your sink there are two valves connected to the supply lines for the sink – one for hot water and one for cold.

If your home has natural gas supplied by the local utility company, you will have a main shut off before the meter, and each appliance where gas is supplied will have an isolation valve. Always remember that natural gas is very combustible and dangerous so be sure to check with your local utility company on how to proceed if you ever smell gas odors inside or around your home. 

4. How wastewater leaves your home

Every home has multiple smaller drain lines that connect to one larger pipe that carries the waste water from your home to the city sewer system or private septic system. This drain system is referred to as the “DWV System” (D – drainage system, W – waste lines, V – vents). The drainage system needs the waste lines to carry the waste out of the home and the waste lines need a vent to allow the water and waste to flow freely through the line.

Think of a vent like a straw in a glass of water: when you put your thumb over the straw before lifting it from the glass, the water will stay in the straw initially and eventually drip very slowly. If you take the same straw out of the glass with your thumb over the top and then lift your thumb, the water quickly drains from the straw. This exposure to air serves as a “vent” for the straw to allow the flow of water. All homes will have at least one main vent existing the roof of the home to the free atmosphere in order to deliver ample air to the DWV system and every fixture. In some cases, group of fixtures will have their own branch vents.

Other key components of the DWV system include:

  • Traps – Along the horizontal drain lines that connect individual fixtures to the DWV System, you will find a U or J shaped bend or p-trap under your sinks. Just like every faucet in your house should have a dedicated shut off valve, every fixture should have a trap. Traps are designed to keep a small amount of water in them after your sink or tub drains, creating a seal that prevents sewer gases and pests from entering your home through your plumbing system. If you have drains in your home that aren’t used very often, such as a drain in the basement, the water in the traps could evaporate and no longer create a seal. In these cases, we recommend installing a drain seal to prevent rodents, insects, odors and gases from entering your home.
  • Clean-outs – It’s also common for waste stacks to have clean-out plugs that provide easy access to remove any blockage or clogs.




Drain Seal

Understanding how your home plumbing system works can help you recognize any problems early and be prepared in case of emergency. To learn about some other common problems for homeowners, check out our blog post “Learn How to Fix These 3 Common Toilet Problems.”

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