Water odors & smells:

This article discusses how to identify, diagnose, and cure common odors that may be present in drinking water. We explain how to get rid of or treat stinks, smells, rotten egg odor, sulphur odors in water.

Also described here: How to diagnose the cause of rotten egg sulphur odors in drinking water. What are other common odors in drinking water and what causes them? Health risks associated with some water odors?

How to get rid of other odors in drinking water. Bacteria including iron-bacteria can produce diesel or fuel oil smells in the water, cucumber smells, and even sewage odors in the water supply.

We also discuss which of these odors may warn of unsanitary conditions.

"Honey - the Water Smells Funny!" - what are the causes of odors in drinking water?

Although water as a pure compound, H₂O, is colorless and odorless, contact with the earth's minerals and our distribution pipes may impart some flavor and odor characteristics.

The Threshold Odor Test Method

A subjective analysis called the Threshold Odor Test, number 2150b. in Standard Methods for the Examination of Water and Wastewater, 19th ed., can give us an idea of the strength of the odor as compared to controls of varying degree of odor concentration.

But how do you interpret what the underlying problem is when your water has a peculiar odor? Just below is a list of articles giving greater detail about the most-common sources of odors in water. At the end of this article you'll find a complete list of water smell & odor diagnosis and correctiion articles.

Cucumber Odors in Water

• See see RED STAINS from WATER SUPPLY where we discuss the effects of iron and iron loving bacteria in a water system. Look for orange slime as well as odors of cucumbers, sewage, or fuel oil in the water.

Diesel Fuel Odors in Water

• See WATER STAINING CONTAMINANTS where we discuss iron-loving bacteria in the water supply that are able to produce a fuel oil or diesel smell in water.

Methane Odors in Water

Methane from natural sources, from coal mining activities, and possibly from other mining or oil drillling activities can explain the presence of significant, even dangerous levels of methane in well water supplies.

• See METHANE GAS SOURCES - possible sources of methane gas in or around buildings? Methane gas (and methane gas production chemicals) in drinking water wells

Sewage Odors in Water

In addition to possible sewage contamination of a well from a nearby failed septic system,

• See HYDROGEN SULFIDE GAS
• See WATER STAINING CONTAMINANTS where we discuss iron-loving bacteria in the water supply. These bacteria can produce a "sewage" odor or even a "cucumber odor".

Sulphur Odors in Water

Some odors are a little more insidious and require a bit of background knowledge to deal with them effectively. If your source water runs through an area where naturally occurring sulfur is present, some sulfur may dissolve into the water. We provide a diagnostic procedure to track down the source of sulphur smells in water just below.

Some of this dissolved sulfur turns to the gas, hydrogen sulfide, and this can give the water a rotten egg type smelly odor.

Sulphur odors can also be caused by a failing hot water heater component, or by certain bacteria in the building plumbing system, conditions we also discuss below.

• See AIR DISCHARGE from HOT WATER - various causes of air discharge and smells at the hot water outlets
• See ANODES & DIP TUBES on WATER HEATERS - a failing water heater or water cylinder anode can produce hydrogen sulfide gas (sulphur smells) in the hot water cylinder and in the building water supply.
• See AIR DISCHARGE from HOT WATER - bubbles, air discharge or odors at hot watrer outlets may be a water heater anode problem, or something else.
• See WATER ODOR DIAGNOSIS - SULPHUR - How to get rid of or treat stinks, smells, rotten egg odor, sulphur odors in water. How to diagnose the cause of rotten egg sulphur odors in drinking water. What are other common odors in drinking water and what causes them? Health risks associated with some water odors? How to get rid of other odors in drinking water
• See SULPHUR & SEWER GAS SMELL SOURCES for detailed list of sewer and sulphur gas odor sources
• See HYDROGEN SULFIDE GAS for a discussion of both sources of sulphur-like smells and the hazards of this gas, including explosion and sewer gas hazards.
• See WATER STAINING CONTAMINANTS for an explanation of how iron and manganese bacteria in a water supply system piping or tanks or heaters and water tanks can produce odors including sewage-like smells.
• See WELL WATER CONTAMINANT SOURCES for an explanation of how sulphur smells in water can also occur in rivers, lakes, streams, ponds, and can be caused by anoxia and algae which in turn may be caused by high nitrogen from agricultural runoff - a condition we discuss
  at

UV & Xenon Light Water Disinfection Equipment Odors

Question: petroleum smell in water after installing UV disinfection system

We installed a UV system in residential home. Water source is well water. The water now has a petroleum type odor - even after several days of running the water.

I did see 2 comments re : odor in the FAQ from Oct 2015 but there was no response as to possible cause. Those were from ships.
Can you advise? - Anonymous by private email, 2018/01/26

Reply: sources of petroleum smell in water do not include UV light itself

UV - ultraviolet light - disinfection would not itself be an odor source. It is simply a light bulb shining light on water to try to kill many species of bacteria that pass by.

If your well has a petroleum odor I suspect it's originating elsewhere - petroleum (heating oil, gasoline, motor oil) would not not be used in the operation nor installation of a UV light water treatment system.

A diagnostic step would be to collect a water sample upstream from the UV light system or right at the well. Have that tested for petroleum products/residues (as those are found in some well water sources).

Also see WATER STAINING CONTAMINANTS where you will see an explanation that iron-loving bacteria in the water supply are able to produce a fuel oil or diesel smell in water.

Note that a UV water disinfection system will not reduce the iron level in your water.

In contrast with U&V light disinfection, Xenon light disinfection has suffered from some ozone-odor complaints. But ozone would smell more like an "electrical" odor not petroleum.

See XENON LAMP OZONE OUTPUT?

Other Odors in Water

• See WELL WATER CONTAMINANT SOURCES - what are the common sources of water pollutants and contaminants?
  Watch Out: Many serious problems (bacteria, heavy metals, nitrates, radon, and many chemicals) can only be found by laboratory testing of water.

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2021-02-07 by John A - water smells bad after installing a UV light

After installing a ultraviolet light on my RO filtration system (after the filter). Our well water stinks like burnt rubber. When I turn off the power to the UV light the stink if gone. I can't even use the UV light. What a waste for us. I do want all the bacteria dead, but the smell is really strong

On 2021-02-07 - by (mod) -

John that's strange indeed. I've installed and used UV lights without any such odor issue related to the light. I would give a call to the manufacturer to ask if they have any advice - and please do tell me what you're told.

By the way, while we want all the bacteria "dead" if there is a too-high level of bacterial contamination or if the water flow is too fast thorugh a UV light, treatment will not be effective, nor will a light remove any other contaminants that might be in water such as chemicals or other odor sources.

On 2019-12-04 by Concerned mother of almost 5 (I'm pregnant) - smells and tastes from plastic water bottles

My husband bought new water bottles that I cleaned extensively with hot soapy water. We just got connected to the community well, because our well went dry. I notice after water sat over night in the reusable water bottle that there was a strong rubbery and lemon peel like smell and taste in the water.

When using a glass cup the smell and taste were more faint coming from our filtered refrigerator. And slightly more noticeable I'm water coming from a 3 gallon filtered y tank contacted to our system, and most pronounced from the water faucet itself. What causes rubber and lemon peel smell and taste in your water?

On 2019-12-11 - by (mod) -

Conc

Let's start by taking a look at the number in the triangle logo found usually on the bottom of your water bottles. What numnber is that? That will tell us the type of plastic used. Some plastics can impart a taste or odor to water.

Next let's look at the data: where where the bottles made. Some suppliers may be using variable plastics that sometimes smell; I've certainly found that to be the case when buying and using polyethylene sheeting.

See PLASTIC RECYCLING CODES, TANKS, TYPES 

and ENDOCRINE DISRUPTERS at BUILDINGS 

On 2018-08-01 by Richard Puckett - I installed a UVA water disinfection filter and within 48 hours I noticed a chemical sme

I installed a UVA water disinfection filter and within 48 hours I noticed a chemical smell -- perhaps the "petroleum" smell others have reported. I note that elsewhere on this page "... iron-loving bacteria in the water supply are able to produce a fuel oil or diesel smell in water."

My well water is very hard and is rich in iron-loving bacteria. I speculate that the UVA light is interacting with the iron bacteria and that they are in the presence of the UVA exuding whatever chemical yields that smell.

On 2018-08-02 by (mod) - after installed a UVA water disinfection filter noticed a chemical smell

Richard

Thank you for an important comment and concern. If the iron content in your water is more than 0.3 mg/L when the water hits the UV light the system will be in trouble.

It sounds as if the UV cannot handle the level of bacteria, combined with high iron content in the water;

If water is high in anything that obscures the light (UV systems use a light not a filter) such as sediment will prevent the light from being effective. On the successful installations I've inspected or installed the UV light was always placed last in the series of water treatment, filters, softeners, etc. for just this reason.

Perhaps installing an iron treatment/removal system upstream from the UV light will solve the problem.

Viqua and other sources note that high iron content in water is a problem for UV treatment - excerpt:
The ideal water quality for UV disinfection is:

Turbidity < 1ntu (turbidity units)
suspended solids < 10mg/l
colour – none
total iron < 0.3 mg/l
manganese < 0.05 mg/l
hardness <7 gpg (120 ppm)

On 2018-07-11 by chester - water may smell if the well is drilled into a coalfield

I was told by a person owning a drilling company if a person smells sulfur the drill hit a coal bed...
if the water smells like onions its cyanide that the drill hit..

I was told this years after going to Mexico and the water smelled of onions and I got sick by using ice in my drinks..

On 2018-02-18 by Concerned Ed - bath water turned yellow and smells

Was running a bath for my 3 year old while she was in the tub and suddenly the water started running bright yellow and had an odor... Is she going to be affectd any way?

On 2017-11-24 - by (mod) -

Ed

Probably not, if the water colour was from iron in your water supply, and provided your child didn't drink the bathwater, but I really don't know. After all we don't know what was in your water.

Most likely it's a iron contaminant, but of course it could be something else.

If you can obtain a sample of your water supply particularly when it is colored but even if it is not, and take that to a water testing lab, you could have them screen for common harmful material such as bacteria and or contaminants found in the water supply in your area, as well as iron.

I do not assume that yellow smelly bathwater is safe for anyone, particularlyi a small child.

Before adding a water treatment system or even considering changing your well, it seems to me it would be a good move to have your well water tested to let you know what the conditions are.

Question: My client complains of a "certain smell" in her water but she can't identify it

I've got a client whose weekend home I inspected in 2005. They now have two young children and she's complaining about a "certain" smell in her water. She can't identify the smell.

Rotten eggs? No. Oily? No. Chemical? No.

But she smells it on herself and on her children after a bath or shower and says her skin fees dry after a shower.

Another twist. They've got two wells. They switch from one to the other when one gets dry. This home is in Ancramdale, NY 12503, Columbia County. Pretty rural. Lots of farming and sheep farming, I think.

The client wants me to test both wells. But I'm not confident that any generic water tests will do the job in this case.

I've looked at both of your articles:

WATER POLLUTANT SOURCES

and WATER SMELLS or ODORS, OTHER

I've looked at these two pages and I've got Smith Lab's price sheet in front of me and I think I'm in over my head.

I mean, this could cost them over $1,000 in lab fees alone for the two wells.

Any suggestions? - Arlene Puentes, ASHI

(Mar 16, 2015) Zyiah said: my water smells

My water smells funny

Reply: Starting Point for Chasing Down Unidentified Odors in the Water Supply

• Most home inspectors, even men and women who include water testing in their services, to not consider tests for unspecified odors in water as within their scope, and indeed ASHI and other inspection standards exclude these tricky environmental questions.
• But you can recommend that your client consult with at least two independent water treatment companies. In her area she can contact Hudson Valley Water Resources - Russ Chapman.
  
  While it's our OPINION that water treatment companies indeed do want to sell water treatment equipment, still they won't make up things that are not there, and they will often agree to inspect a client's water treatment equipment and test her water at no fee.
• Also, local water testing laboratories, folks who process a large volume of water samples from their neighborhood, often can tell you (or your client) whether or not they've had odor complaints from other homeowners in the same neighborhood.
• Your client might also check these other possibilities:
• A more comprehensive starting point for tracking down smells in household water begins
  
  at ODORS IN WATER.
• There could be odors coming from a source other than water. She should consult our odor track down approach beginning
  
  at ODORS GASES SMELLS, DIAGNOSIS & CURE, where we consider all common sources of odors in buildings, including water and other systems.
• Check the soaps, gels, shampoos, lotions in use because sometimes they may have a role in these complaints

Who smells the odors?

• Individual sense of smell varies widely. But if only one person observes an odor or other environmental complaint, some further investigation in an additional direction (besides the building and its neighborhood and its mechanical systems) could be helpful.
• Watch out: in some cases, particularly where there were health or aging concerns involved, sometimes these complaints are psychogenic in origin, or on occasion a person might have a health related problem that affects odors and skin sensations. Your client is not elderly, so aging-related health and odor complaints probably wouldn't apply.
  
  But if she is the only person observing the odor complaint, it's worth an effort to sort out this question:
• Is the individual observing these odors because s/he has a particularly sensitive sense of smell, or could there be an underlying health or neurological problem that has not been recognized.
  
  If there is even the slightest possibility of the second alternative, the client ought to check with her primary care physician and with that doctor, decide if a referral to a suitable neurologist is in order.

Watch out: methane odors in a building water supply can be explosive (METHANE GAS SOURCES)

Scott Bradley, Aquacheck Water Testing Laboratory contributed content to this article.

 

On 2012-12-13 by Paul - hotter water will fix odors

Problem: -- Bacteria - Rotten Egg Smell in your Hot Side of your Water Heater

When the bacterium enters a domestic water system it can find an ideal host environment of warm water temperatures (105-115°F), stagnant water areas (storage tanks and dead-end piping legs) and ample food sources (sediment, scale, deposits and biofilm). Under these conditions can rapidly colonize, forming higher concentrations that can pose the public health threat of Disease.

There are many methods of controlling colonization of bacteria. However, a widely accepted and preferred method is to maintain the hot water system storage temperature continually at or above 140°F.

Unfortunately, the elevated temperature necessary to minimize the growth of and kill bacteria has the potential to cause serious thermal shock and scalding injuries . Solution: - Watts Thermostatic Mixing Valves maintain and limit the mixed hot water to a desirable, selectable temperature allowing for the storage of domestic hot water at the higher temperatures necessary to reduce the risk of growth in the system.

install a mixing valve on the output of your water heater, and turn up the water heater to 140 F and adjust the mixing valve output temp to 120 F, give it 1 week to kill the bugs in the water heater, and then you should be Done with the problem

On 2012-12-13 by (mod) - not necessarily correct

Thanks for the odor cure suggestion, Paul. You're right that water heaters that are not kept hot-enough may breed bacteria that may not only smell but may be unhealthy.

However as we explain in this article series, there are many other sources of odors or smells in the water supply that won't be fixed by heating it up, such as sulphur smells originating in the well or other odor sources: chemical contaminants.

On 2012-10-20 by Mike G - lead mines and Scottish Highlander cows pooping in our water source

There are lead mines in this town, and a whole heard of Scotish Highlanders cows walking through the center where there is a major brook they walk through. a whole host of possible problems, and when its not raining the water runs slowly throughy the area causing a slow moving swamp enviroment

On 2012-08-24 by Heather Marsh - rotten egg smell

I smell this rotten egg smell in the bathroom downstairs when someone is taking a shower in the bathroom above. We have a septic system. What type of contractor do I contact to remedy this?

On 2012-08-11 by cheryl - rotten fishey smell in my tap water?

what do I do if smell A rotten fishey smell in my tap water?

On 2012-08-11 by (mod)

Check for sulphur, bacteria, and consider one of the treatment methods discussed here

On 2012-07-01 by Heather - find the source of a smell at one fixture

after installing a sink in the upstairs of the house with metal pipes, the water gives off an odd smell= possibly like old plastic and is stronger if the water hasnt been run for a day. All the other sinks/baths in the house do not have this problem. Im lost as to what it could be or how to go about fixing it

On 2012-07-01 by (mod)

When the smell is just at one fixture I figure the problem isn't the water supply itself; start by cleaning the sink and its trap.

Then check that the sink drain is properly connected to a plumbing vent pipe.

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Continue reading at WATER ODOR DIAGNOSIS - SULPHUR or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see WATER ODOR FAQs - questions & answers about smells in water that were posted originally at this page.

Or see these

Recommended Articles

• WATER ODORS, CAUSE CURE - home
  • ANODES & DIP TUBES on WATER HEATERS
  • CHLORINE SOURCES in DRINKING WATER
  • CHLORINATION WELL SHOCKING PROCEDURE
  • WATER SOFTENER ADJUSTMENT & CONTROLS
  • WATER SOFTENER CLEANING & SANITIZING
  • WATER ODOR DIAGNOSIS - SULPHUR
  • WATER ODOR TREATMENTS, CURES - SULPHUR
  • WATER SMELLS or ODORS, OTHER
  • WATER POLLUTANT SOURCES
  • WATER STAINING CONTAMINANTS
    
• WATER POLLUTANT SOURCES
• WATER TESTS for CONTAMINANTS

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INDEX to RELATED ARTICLES: ARTICLE INDEX to BUILDING ODOR DIAGNOSIS & CURE

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