MySepticStinks.com

Stop conditions

A smell is an arrival, not an address

Something stinks. Your nose is right about that, and about almost nothing else.

A smell tells you that something reached you. It does not tell you what it is, where it started, how far away it is, or whether it is getting worse. So this page never guesses the cause. It is arranged by time instead — what to do before anything else, in the first five minutes, before you call someone, and over the next few days.

“Septic” in the name of this site is your hypothesis, not our conclusion. It may turn out to be plumbing, a public sewer, an RV tank, the water itself, the weather, or something with nothing to do with wastewater at all.

Start with the stop conditions Nobody is in danger — where do I start?

Walking a smell backwards A single small solid square near the bottom right is labelled “you”. Above and to the left of it a soft cloud spreads out and fades away, with no boundary anywhere. Five faint dashed paths lead back from you into the cloud, and each one dissolves before it reaches anything. Nothing in the picture has a hard edge except you. you
Every path back dissolves before it reaches anything. That is not a flaw in the drawing — it is the honest picture. Anything on this page with a hard edge is something that is actually known. The smell has no edge.

Before anything else

Five conditions that stop everything else on this page

If any of these describes what is happening, stop reading, act, and come back later. None of them requires you to know what the smell is.

  1. You think it could be a gas leak.

    A smell cannot identify a gas. Rotten eggs is the odour of hydrogen sulfide, of the odorant added to natural gas, of sulfur in well water, and of other things besides. Because your nose cannot tell them apart, a suspected leak is treated as a leak.

    Do Leave. Do not use a flame or a lighter, do not smoke, do not switch anything on or off, and do not start a vehicle in the suspected area. From somewhere else, call 911 or your gas utility’s emergency number.

  2. Someone has symptoms.

    Headache, eye or throat irritation, nausea, dizziness, trouble breathing, confusion, or collapse. OSHA describes the effects of hydrogen sulfide as ranging from headaches and eye irritation to unconsciousness and death, and notes that it can overcome an unprepared person almost immediately.

    Do Get them into fresh air. Call 911 for anything serious. Tell a healthcare professional what they may have been exposed to — do not try to name the gas yourself.

  3. A tank, pit, manhole, or crawlspace is involved.

    OSHA: hydrogen sulfide is heavier than air, may travel along the ground, and builds up in low-lying areas and in confined spaces such as sewers, manholes, and vaults. It can overcome unprepared people including rescuers.

    Do Do not go in. Do not lean in. Do not go in after someone. Keep others back and call 911 — a confined-space rescue needs responders with equipment you do not have.

  4. Sewage is where people are.

    Backing up into the building, standing on the ground, or running towards a well, a creek, a pond, or a place people swim. EPA describes surfacing untreated wastewater as a direct public-health hazard and notes that children and pets can be exposed without knowing it.

    Do Keep people and animals away and out of contact. EPA advises avoiding contact with the sewage and contacting your local health department or regulatory agency for guidance. If anyone has been exposed, contact a health professional.

  5. There is fire, smoke, or exposed electrical danger.

    Including a control panel, pump, or blower that is sparking, smoking, submerged, or has damaged wiring.

    Do Do not open it, dry it, reset it, or bypass an alarm. Call 911 for fire, and your electricity provider or a licensed electrician for the rest.

If the smell fades, that is not an all-clear. OSHA states that with hydrogen sulfide, after a while at low concentrations — or more quickly at high ones — you can no longer smell it to warn you it is there. NIOSH’s review of the same gas reports olfactory fatigue at 100 ppm, which is also its revised value for a concentration immediately dangerous to life or health. Those are occupational figures and not a home test; the useful part is the shape of the curve. Your nose gets quieter as the situation gets worse.

And the other way round: not knowing what a smell is, is not evidence that anything is dangerous or failing. The five conditions above are things you can observe. Uncertainty is not one of them. If none of them is happening, you are not in an emergency — you are in a question, and the rest of this page is about questions.

Why there is no map on this page

Your nose is a very good detector and a very poor witness.

It is the only instrument you have, it works instantly, and it has already finished its whole job: it told you to pay attention. Almost everything people ask it next, it cannot answer.

What it actually established

  • Something is in the air where you are.
  • Roughly when it started, and whether it comes and goes.
  • Whether it changes with weather, water use, or time of day.
  • That it is strong enough to notice — which is worth writing down.

Those are real observations. They are also the whole list.

What it did not

  • What the substance is. Very different things smell the same.
  • Where it came from. Air moves. The strongest smell is not the source.
  • How far away it is. A low enclosed space concentrates whatever reaches it.
  • Whether it is getting worse. The nose fades before the hazard does.
  • Whether it is septic at all. That part was a guess in a domain name.

No amount of careful sniffing moves an item from this column to the other one.

“It is not possible to diagnose the exact cause of an odor remotely.”

That sentence is why the rest of this page is organised by when rather than by what. Take the map away, and the clock is what is left.

In the first minute

Three things that outrank where you are standing

If one of these is true, it decides the first call — whichever of the seven places below matches you.

Sign 01

You can see wastewater, or ground that should not be wet

A backup into the building, standing water or damp spots over a tank or drainfield, a pipe discharging to the surface, or bright green spongy grass over the system in dry weather. EPA lists soft, wet, or spongy soil around a drainfield — especially when there has been no significant rainfall — as a good indication of system failure.

First call Your local health department, or the county office that holds on-site sewage authority government authority — before a contractor, because a public-health question is not a contractor’s to close.

Does not establish whose fault it is, whether a rule was broken, what failed, or what the repair is.

Sign 02

An alarm, a pump, a blower, or a power problem

Aerobic and other advanced treatment systems have moving parts, electricity, and maintenance obligations that a plain tank-and-drainfield system does not. EPA notes that alternative systems with float switches, pumps, or mechanical components should be inspected more often and that a service contract matters. An alarm is the system asking for its own technician.

First call The licensed maintenance provider named on your service contract private company, or your county authority if you do not know who holds the contract.

Does not establish which component failed, or whether the system is in or out of compliance. Read the alarm from outside. Do not open energised controls, disable it, or change timer settings.

Sign 03

A well, a pond, a creek, or a swimming place is nearby

EPA: if a septic system is not working properly, or is located too close to a drinking water well, contaminants from the wastewater can end up in drinking water, and surface waters can be contaminated with pathogens and nutrients.

First call Your local health department government authority, plus a certified drinking-water laboratory private company if the well is yours.

Does not establish that the water is contaminated. Proximity is a reason to test, not a result — and water that smells fine is not a clearance either.

In the first five minutes

Where are you standing when you smell it?

Not what do you think it is — that question has no safe answer from here. Where you are standing is something you actually know, and it is enough to name who owns the first answer. Pick the closest one. “I can’t tell” is on the list, and it is a real answer rather than a failure.

01

Inside, at a fixture or a drain

A bathroom, a floor drain, a laundry, a kitchen sink, a shower nobody has used for a while, a cleanout inside the building.

What you can note from where you stand
Which room and which fixture. Whether other fixtures are affected or only one. Whether anything drains slowly or gurgles. Whether that fixture has gone unused for days or weeks. Whether running an extractor fan, running the air conditioning, or opening a window makes it stronger or weaker.
Who owns the first answer
A licensed plumber private company. If the property is on public sewer and neighbours smell it too, call the utility first — see 05.
What being here does not prove
EPA lists a roof vent or other vent pipe doing its normal job, a vent obstructed by leaves or debris, a vent frozen during a prolonged cold spell, a wind down-draft, and other location-specific conditions among the possible reasons for an odour, alongside a drainfield that is not working properly. An indoor smell does not pick between them, and it does not prove a dry trap, a sewer lateral, a gas, or a septic failure.
Do not
Do not test with a flame. Do not pour drain chemicals in to find out — EPA advises avoiding chemical drain openers on a septic system, and warns against pouring household chemicals down the drain at all.

02

In a basement, a crawlspace, a pit, or another low enclosed space

This one has its own card because of physics, not because of plumbing.

Hydrogen sulfide is heavier than air, may travel along the ground, and builds up in low-lying and confined spaces. Do not go down there to find the smell. Read the rest of this card from the doorway.

What you can note from where you stand
Whether the space is ventilated at all. Whether anything is visibly wet, and whether a sump or a pump is down there. When it started, and whether it is worse after rain. Whether the smell is present upstairs too, or only at the opening.
Who owns the first answer
A licensed plumber private company — or your gas utility’s emergency line public utility first, if you think it could be gas.
What being here does not prove
A low space concentrates whatever reaches it. The smell being strongest in the basement does not mean the source is in the basement, and strength tells you nothing about concentration. Your nose is not a meter.
Do not
Do not enter to investigate. Do not send anyone else in. Do not go in after a person or a pet — OSHA notes that hydrogen sulfide can almost immediately overcome unprepared people, including rescuers. That is a 911 call, not a favour.

03

Outside, near a tank, a treatment unit, or the yard

A known private system: a tank lid, a pump tank, an aerobic unit, spray heads, a drainfield, or just the part of the yard where you know it lives.

What you can note from where you stand
From a safe distance: soft, wet, or spongy ground, standing water, unusually lush grass. When the smell started, and what the weather has been. When the tank was last pumped, and what the last service report said. Whether there is a maintenance contract, and with whom. Whether there is an alarm light or sound.
Who owns the first answer
A licensed on-site sewage professional for your system type private company — maintenance, repair, or pumping, depending on the question. If you think wastewater is reaching the surface or leaving the property, the county office holding on-site sewage authority government authority comes first instead.
What being here does not prove
Nothing about failure. EPA states that it is not possible to diagnose the exact cause of an odour remotely, and a person standing in their own yard is also outside the tank. Pumping, inspection, maintenance, repair, permit, and approval are six different events; a pumping receipt is evidence that a service happened, not proof that a system works.
Do not
Do not open a lid to look — a person can fall in, and the air inside a tank is not the air outside it. Do not dig into the drainfield, drive on it, or pour an additive in to mask the smell.
If you are choosing a company
OnSiteSewage.com private company is a licensed Texas on-site sewage contractor and is one option here — only if the question is genuinely about a private on-site system, only if the work is within its current scope, and only if your address is inside its coverage. It is not the answer to a gas question, a plumbing question, a public-sewer question, an RV question, a water-quality question, or a regulatory question, and it does not speak for any authority. If none of that fits, this page is finished with us and you should call somebody else.

04

In or around an RV, a boat, or a mobile home

A holding tank, a coach toilet, a sewer hose, a park pedestal, a marina pump-out.

Most writing about “septic smell” assumes a house. Many RV toilets use a seal at the bottom of the bowl rather than a P-trap, and a holding tank is not a septic tank. Do not apply house advice here without checking that it fits the vehicle.

What you can note from where you stand
Inside the coach or outside it. Black tank or grey tank, if you know. Whether it tracks with the toilet, the shower drain, the vent, the hose, or the park’s connection. How hot it has been, and for how long. How long since it was dumped, whether you have been travelling, and whether it has been sitting unused. Whether anyone else in the park has it too. Any visible leak at the hose or fitting, seen from a safe distance.
Who owns the first answer
Your manufacturer’s guidance, or an RV service technician private company — or the park or marina operator private company if the smell is at their connection, or others in the park have it too.
What being here does not prove
Heat is a well-known trigger for holding-tank odour, and it proves nothing about a fault. It does not establish a failed seal, a blocked vent, a cracked tank, a bad park connection, or a problem in whatever system the park connects to downstream. All of those stay open, and the last one is not yours.
Do not
Do not treat a deodorising chemical as a repair — EPA’s factsheet for RV, boat, and mobile-home owners covers the dangers of chemical additives including holding-tank deodorisers. Do not discharge anywhere but an approved facility. Do not open a tank or climb into a pit at a dump station.

05

At the street, a manhole, or across several properties

If it is outdoors and other people are noticing it too, it is probably not only yours.

What you can note from where you stand
The public location — an intersection, a manhole cover, a lift station, a ditch. The time, and how long it lasts. Roughly how many properties. Which way the wind is blowing. Whether the utility has posted a notice or is working nearby.
Who owns the first answer
Your city, water utility, or sewer district public utility or government authority. Report it from a safe public place.
What being here does not prove
Not whether the source is a main, a lateral, a building, a lift station, or a private system on somebody’s land. A smell in the street does not identify a property, and it is not a reason to name a neighbour.
Do not
Do not lift a manhole cover. Do not enter a utility structure. Do not follow it into a ditch.

06

In the water itself — hot taps, cold taps, or the water heater

If the smell arrives with the water and leaves when the tap is off, this is a water question before it is a wastewater question.

What you can note from where you stand
Hot only, cold only, or both. One fixture or every fixture. Whether it fades after the water has run for a minute. Whether the property is on a private well or on public water. When the water heater was last serviced, if you know.
Who owns the first answer
On public water, your water utility public utility. On a private well, your local health department government authority or a certified drinking-water laboratory private company. For hot-water-only odour, a licensed plumber private company.
What being here does not prove
Sulfur in water does not prove that sewage has reached it, and it does not measure any gas in the air. Equally, water that smells fine is not evidence that a well is uncontaminated — that is what a test is for.
Do not
Do not drink water you are worried about while you wait for an answer.

07

Somewhere else, or I can’t tell

Outdoors with nothing obvious around. Drifting in on certain days. At the front of the property and gone at the back. Or simply: you cannot pin it down.

What you can note from where you stand
Time of day, and how long it lasts. Wind and weather. Which direction it seems to come from — noting that this is unreliable, and writing it down anyway. Whether it follows rain, heat, freezing, a recent service visit, travel, a week with no water use, or a change in how many people are in the house. What is upwind: a farm, a lift station, a plant, a ditch, a neighbour’s system, a dead animal.
Who owns the first answer
Nobody yet, and that is a legitimate place to be. Start the log below. If it is persistent, outdoors, and you cannot identify a source, your local health or environmental authority government authority is the right place to ask whether anyone else has reported it.
What being here does not prove
Nothing at all, in either direction. An unanswered question is not a warning sign. A thin file is a thin file. The next change is what will tell you something, and a written record is what will let you recognise it when it arrives.

Before you call

Nobody on this list can tell you what the smell is.

Not over the phone, and not from your description. What each of them can do is different, and knowing which is which is most of what saves a wasted week. Five kinds of voice, and they are not interchangeable.

  1. A state rule

    The Texas statutes and the TCEQ rules made under them

    Ask it what the minimum is anywhere in Texas.

    Do not expect it to describe what applies at your address. A local authorised agent may be stricter than the statewide minimum, which makes “Texas requires…” unsafe shorthand for anything a local order controls.

  2. State agency guidance

    TCEQ · government authority

    Ask it how the programme works, who your local contact is, and how a complaint is made.

    Do not expect a determination about your property. Guidance explains a system; it does not adjudicate a smell.

  3. Your local authority

    The county or city acting as TCEQ’s authorised agent, and the local health department · government authority

    Ask it what is required here, whether what you are describing is something they investigate, and whether anyone else has reported it.

    Do not expect them to repair anything, to answer the same day, or to be bound by what the next county does.

  4. A licensed professional

    Plumber, on-site maintenance provider, installer, pumper, designer, engineer · private company

    Ask it what they found at your property, in writing, within their licence and scope — and what they did not look at.

    Do not expect a licence to turn a company’s opinion into a rule, or one trade’s findings to close another trade’s question.

  5. A private company’s recommendation

    Anyone selling a service or a product, including ours · private company

    Ask it what it can do, what it charges, and whether it serves your address.

    Do not expect it to own a public-health, utility, gas, or regulatory decision. Being able to do the work is not the same as being the one who decides the work is needed.

This is not a ranking of people. It ranks what an answer can settle. A plumber can be completely right about the thing they were asked and completely silent about the thing that matters — and so can a regulator.

This site does not place calls, take your details, or pass anything to anyone. There is nothing here to fill in, and nothing is saved on your device. Every phone number and web address on this page belongs to somebody else, and you go to them directly.

Over the next few days

The most useful thing you can hand a professional is a piece of paper.

A smell that comes and goes is nearly impossible to describe from memory, and it is exactly the kind that stays unsolved. Written times, dated, are worth more than any adjective. If the smell is intermittent and none of the stop conditions applies, this is the next step — not a consolation prize for failing to find an answer.

Each time you notice it, write down

  1. Date and clock time, and how long it lasted.
  2. Where you were — the room, the fixture, the part of the yard, the street.
  3. How strong, in your own words. Being consistent matters more than the vocabulary.
  4. Weather — temperature, rain in the last few days, wind direction, freezing, drought.
  5. Water use — laundry, long showers, guests, a party, or nobody home for a week.
  6. Anything recent — pumping, service, a repair, an installation, landscaping, heavy equipment on the yard, a remodel, flooding.
  7. Anything else you could see or hear — slow drains, gurgling, an alarm, a pump running or not running, wet ground.
  8. Whether anyone else noticed it — in the house, next door, in the park, in the street.

And find these once, before you call

  1. The permit or as-built drawing for the system, if there is one.
  2. The system type — plain tank and drainfield, aerobic, spray, drip, mound, holding tank, public sewer, or unknown.
  3. The maintenance contract, and who holds it.
  4. The date of the last pump-out, and the last service report.
  5. Whether the property is on a private well or public water.
  6. For an RV: the owner’s manual, and the park’s rules.

Keeping a log is not a safety clearance and it is not a diagnosis. It is the raw material somebody else needs in order to do their job. If a stop condition appears while you are keeping it, the log stops and the stop condition wins.

Back to the stop conditions Printing this page gives you the stop conditions, this log, and the questions to ask — on paper, next to the phone.

After the smell

This page only covers the moment you noticed something.

It deliberately stops there. These are separate sites with different jobs, and each one is labelled by what kind of thing it is.

Where this came from

Sources

Every factual claim above traces to one of these. Links were checked on 9 September 2026. The safety facts are federal and apply anywhere; the routing to authorities is written for Texas, and elsewhere the roles are similar but the offices are different.

  1. EPA — Resolving Septic System Malfunctions federal agency The odour question, the “not possible to diagnose the exact cause of an odor remotely” statement, signs of a failing system, and what to do when a home floods.
  2. EPA — How to Care for Your Septic System federal agency Inspection and pumping intervals, why systems with float switches, pumps, or mechanical components need a service contract, water use, and what not to put down a drain.
  3. EPA — Septic System Impacts on Water Sources federal agency Surfacing untreated wastewater as a direct public-health hazard, exposure of children and pets, wells, and surface water.
  4. EPA — Safe Wastewater Disposal for RV, Boat, and Mobile Home Owners and Operators federal agency Holding-tank wastewater, and the dangers of chemical additives such as deodorisers.
  5. OSHA — Hydrogen Sulfide federal agency Flammable and toxic even at low concentrations, heavier than air, travels along the ground, builds up in low-lying and confined spaces, can no longer be smelled as a warning, and can overcome unprepared people including rescuers.
  6. NIOSH — Hydrogen Sulfide, Immediately Dangerous to Life or Health value federal agency The revised IDLH of 100 ppm, the rotten-egg description, and the reported onset of olfactory fatigue. These are occupational values, not a home test.
  7. TCEQ — On-Site Sewage Facilities (Including Septic Systems) state agency The Texas programme, authorised agents, licensing, and how complaints are made.
  8. TCEQ — Find your local on-site sewage contact by county state agency The authority record that names which office holds on-site sewage authority where you are.