How Does Plumbing Work?

A Simple Guide from Drain Pro Plumbing & Septic in Western Washington

If you’ve ever asked yourself, “How does plumbing work in a house?” — you’re not alone. At Drain Pro Plumbing & Septic, we frequently help homeowners across Western Washington, including Renton, Kent, and nearby areas, understand the basics of their home plumbing system.

Your plumbing system plays a crucial role in keeping your household safe, clean, and comfortable. Whether you’re troubleshooting a clogged drain, experiencing low water pressure, or noticing a slow-draining sink, learning how a plumbing system works can help you recognize problems early and know when to call a professional plumber.

What Is a Plumbing System and How Does It Work?

A residential plumbing system is made up of two main subsystems: the water supply system and the drain-waste-vent (DWV) system. These work together to bring in clean water and remove wastewater from your home safely and efficiently.

1. Water Supply System – Bringing Clean Water In

Your home’s water supply system is responsible for delivering clean, pressurized water from the source to all the plumbing fixtures inside your home.

• Water Source: Most homes in King and Pierce counties receive water from a municipal supply, though rural homes may rely on private wells.

• Pipes: Supply lines are typically made of copper, PEX (cross-linked polyethylene), or PVC.

• Fixtures: These include faucets, toilets, showers, dishwashers, washing machines, and water heaters.

• Shutoff Valve: Every home has a main water shutoff valve that allows you to stop the flow of water in case of an emergency or repair.

When you turn on a faucet, water flows through these pipes under pressure, providing instant access to clean water. This pressure is what allows water to travel upward to upper stories and out of your fixtures with force.

2. Drain-Waste-Vent (DWV) System – Removing Wastewater Safely

The DWV plumbing system is equally essential. It removes used water and waste from your home and vents harmful gases safely outside.

Key Components of the DWV System:

• Drain Pipes: These carry gray water and black water from sinks, bathtubs, showers, toilets, and appliances.

• Traps (P-Traps and S-Traps): These U-shaped pipes hold a small amount of water to prevent sewer gases from coming back into the home.

• Vent Pipes (Plumbing Vents): These vertical pipes allow air into the drain lines. Plumbing vents keep pressure balanced and ensure wastewater flows properly.

• Main Sewer Line or Septic System: Wastewater either flows into a municipal sewer system or into a private septic tank for treatment and dispersal.

If you live in a rural area of Western Washington, your home might rely on a septic system. In this case, solids settle inside the septic tank while liquids are filtered and absorbed into a drain field.

Why Plumbing Vents Matter

Plumbing vents, also called vent stacks, are a critical (but often overlooked) part of the DWV system. They allow fresh air into the plumbing lines, which helps wastewater drain smoothly and prevents airlocks or suction that can slow drainage. Without proper venting, you may experience slow drains, gurgling sounds, or even harmful gas buildup.

Common Plumbing Issues We See in Western Washington

Even with a well-installed plumbing system, problems can happen over time. Here are the most common plumbing issues we help homeowners with at Drain Pro Plumbing & Septic:

• Leaky pipes or faucets – Often caused by corrosion, shifting pipes, or worn-out seals

• Clogged toilets or drains – Usually due to grease, hair, food particles, or non-flushable items

• Low water pressure – A sign of pipe corrosion, mineral buildup, or hidden leaks

• Sewer line blockages – Often caused by tree root intrusion, collapsed pipes, or foreign objects

• Septic tank backups – A warning sign that your septic system is overdue for pumping or has a more serious issue

When Should You Call a Local Plumber?

If you notice signs like water backing up, slow drains, bubbling toilets, or unusual smells, it’s time to call a trusted plumber near you. DIY plumbing repairs can lead to larger, more expensive issues if not done correctly.

At Drain Pro Plumbing & Septic, we provide expert plumbing and septic services across Renton, Kent, Auburn, Tacoma, and the greater Western Washington area.

Our Services Include:

• Emergency plumbing repairs

• Septic tank pumping and inspections

• Drain cleaning and hydro jetting

• Sewer line cleaning and replacement

• Fixture installation and water heater services

• Plumbing system inspections and leak detection

Protect Your Home – Know How Your Plumbing System Works

Understanding how your home plumbing system works is the first step toward preventing water damage, saving on repair costs, and ensuring the health and safety of your family. Don’t ignore strange plumbing sounds, bad odors, or persistent clogs—let our licensed professionals take a look.

Call Drain Pro Plumbing & Septic Today

• Locally owned and operated

• Fully licensed, bonded, and insured

• Trusted by Western Washington homeowners for over a decade

Contact us today or schedule service online for fast, professional help with all your plumbing and septic needs.

Drain Pro Plumbing & Septic
Your trusted plumbing and septic experts serving Renton, Kent, Auburn, Tacoma, and surrounding areas in Western Washington.