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Why Does My Water Smell Bad? Common Plumbing Causes

Written by Pilot Plumbing Marketing | Jul 14, 2026

You turn on the faucet to fill a glass of water or step into the shower, and suddenly you're greeted by an unpleasant odor. Whether it's a rotten egg smell, a metallic scent, or something musty, foul-smelling water is never something homeowners want to experience. While many water odors are harmless, they can also point to plumbing issues that shouldn't be ignored.

Understanding what causes water to smell bad can help you determine whether it's a simple maintenance issue or time to call a professional plumber. At Pilot Plumbing, we help homeowners throughout the North Houston area diagnose and resolve water quality concerns quickly and effectively.

Is Smelly Water Safe?

In many cases, unpleasant-smelling water is caused by naturally occurring minerals, bacteria, or reactions inside your plumbing system, not necessarily harmful contamination. However, persistent odors should never be ignored because they can indicate issues with your plumbing, water heater, or water source that may worsen over time. The City of Houston notes that naturally occurring compounds such as hydrogen sulfide, iron, manganese, geosmin, and MIB can affect the taste and odor of drinking water without necessarily impacting its safety.

The first step is identifying exactly what the water smells like and whether the odor occurs in hot water, cold water, or both.

Did you know? The average American uses approximately 82 gallons of water per day for household activities, meaning your plumbing system moves thousands of gallons through your home every month.

Rotten Egg Smell: The Most Common Complaint

If your water smells like rotten eggs, the culprit is usually hydrogen sulfide gas.

This odor commonly develops when sulfur bacteria interact with minerals inside your plumbing or water heater. The bacteria themselves are typically not harmful, but the smell is certainly unpleasant.

Ask yourself:

    • Does only the hot water smell?
    • Does every faucet smell?
    • Is the odor stronger after the water has been sitting unused?

If the smell only occurs when using hot water, your water heater is often the source of the problem. A reaction between sulfur bacteria and the anode rod inside the tank can create hydrogen sulfide gas. Mineral buildup and sediment inside the tank can make the problem even worse.

Your Water Heater Could Be the Problem

Many homeowners assume smelly water means something is wrong with the city's water supply, but water heaters are one of the most common sources of odor.

Over time, water heaters collect:

    • Sediment
    • Hard water minerals
    • Bacteria
    • Corrosion

These conditions create an ideal environment for unpleasant odors to develop.

In fact, regular water heater flushing is one of the simplest ways to improve water quality and extend the life of the unit. According to the U.S. Environmental Protection Agency, sediment buildup reduces efficiency and can shorten the lifespan of water heaters. It is recommended to flush your water heater once a year.

Signs your water heater may be responsible include:

    • Only hot water smells
    • Water appears cloudy
    • Strange popping or rumbling noises
    • Reduced hot water supply
    • Older water heater (8–12+ years)

A professional inspection can determine whether the tank simply needs maintenance or whether replacement is the better long-term solution.

Musty or Earthy-Smelling Water

Water that smells musty, moldy, or earthy is often related to naturally occurring organic compounds.

In municipal water systems, seasonal algae blooms can create compounds known as geosmin and MIB (2-methylisoborneol). These compounds can produce noticeable earthy odors even at extremely low concentrations. While unpleasant, they generally affect taste and smell rather than safety.

Inside your home, a musty smell can also result from:

    • Biofilm inside drain lines
    • Iron bacteria
    • Water sitting in rarely used pipes
    • Dirty sink overflows or garbage disposals

Sometimes homeowners think the water itself smells when the real culprit is bacteria growing inside the sink drain or overflow opening.

Did you know? Humans can detect geosmin, the compound responsible for earthy-smelling water, at concentrations as low as 5 parts per trillion, making our noses incredibly sensitive even when water remains safe to drink.

Metallic-Smelling Water

If your water has a metallic taste or smell, minerals are usually to blame.

Possible causes include:

    • Iron
    • Manganese
    • Copper
    • Aging galvanized pipes
    • Corroding plumbing fixtures

Older homes may experience metallic odors as plumbing materials begin to deteriorate over time.

Besides affecting taste, excessive corrosion can eventually lead to leaks, reduced water pressure, or discolored water. If you notice blue-green stains around fixtures or rusty-colored water, it's a good idea to have your plumbing system evaluated.

Sewer Odors Around Your Sink

Sometimes homeowners believe their water smells bad when the odor is actually coming from the drain.

Common plumbing causes include:

    • Dry P-traps
    • Clogged vents
    • Sewer gas entering the home
    • Organic buildup inside drains
    • Loose plumbing connections

If the smell gets stronger while the water is running but not from the water itself, the issue may be inside your drainage system rather than your drinking water. Sewer gas odors should be inspected promptly because they can indicate plumbing vent or drain problems.

Why Does the Smell Come and Go?

Many homeowners notice that water odors seem to appear only occasionally.

Several factors can cause temporary odor changes:

    • Seasonal changes in municipal water
    • Increased groundwater usage
    • Water sitting in pipes overnight
    • Long vacations or unused plumbing fixtures
    • Heavy rainfall
    • Water heater inactivity

For example, Houston's water supply can vary between surface water and groundwater sources depending on demand, which may temporarily change the taste or smell of tap water.

What Should You Do If Your Water Smells Bad?

If you notice an unusual odor, try narrowing down the source:

    • Test both hot and cold water
    • Check multiple faucets throughout the house
    • Determine whether the smell comes from the water or the drain
    • Note when the odor occurs (morning, after vacations, only after hot water use)
    • Watch for discoloration or changes in water pressure

Avoid assuming the problem will simply disappear. Many plumbing issues become more expensive when left untreated.

When to Call a Professional Plumber

While some odor issues can be solved by flushing a rarely used faucet or cleaning a drain, others require professional diagnosis.

You should contact a plumber if:

    • The smell persists for several days
    • Multiple fixtures are affected
    • Only hot water smells
    • Water is discolored
    • You notice reduced water pressure
    • Sewer odors are present inside the home
    • Your water heater hasn't been serviced in years

A licensed plumber can inspect your plumbing system, water heater, drains, and water supply to identify the exact cause and recommend the right solution.

Don't Let Bad-Smelling Water Become a Bigger Problem

Water should be clean, fresh, and odor-free. If unpleasant smells are coming from your faucets, your plumbing system is trying to tell you something. Whether it's a water heater that needs maintenance, aging pipes, drain buildup, or another plumbing issue, addressing the problem early can help prevent larger repairs and restore your confidence in your home's water.

If you're dealing with foul-smelling water, the experienced team at Pilot Plumbing is here to help. Our licensed plumbers can quickly diagnose the source of the odor, recommend the most effective solution, and restore clean, fresh-smelling water to your home. Contact Pilot Plumbing today to schedule an inspection and enjoy peace of mind knowing your plumbing system is in expert hands.