Quick answer: When a water heater is installed wrong, five problems show up over and over: the unit is the wrong size, the thermal expansion tank is missing, there’s no sediment trap on the gas line, the venting or safety valve setup doesn’t meet code, and hard water sediment builds up faster than it should. Each one can shorten the tank’s life, void the warranty, or give an insurer a reason to deny a future water damage claim.
A new water heater shouldn’t rumble, pop, or run cold by the second shower. When it does, the tank usually isn’t the problem. The install is.
We’re Tennessee’s Choice Plumbing, based in Dresden, and we get called out to a lot of water heaters that were swapped in a hurry, either by a homeowner or by someone unlicensed. The unit on the wall often looks fine. The trouble is hidden in the details around it. If yours started acting up soon after a replacement, it’s smart to have it looked at before you blame the tank, since a quick water heater repair visit can catch a code miss early and save the unit.
Here are the five issues we run into most, along with the data behind why they matter.
Issue 1: The Water Heater Is the Wrong Size for the Home
One of the most common mistakes we see is a tank that doesn’t match the household. Too small, and you run out of hot water during back-to-back showers or a full load of laundry. Too big, and you pay to heat water nobody uses.
About 97% of U.S. water heaters are the traditional storage-tank style, usually in the 25 to 100 gallon range for homes. Picking the right gallon count depends on the number of people, the number of bathrooms, and your peak hour of use, not just whatever was on the truck that day.
There’s no single “correct” size for every house. The honest move is to size it to your actual demand, which a licensed plumber can calculate during the visit.
Issue 2: A Missing or Improper Thermal Expansion Tank
When cold water heats up, it expands. In a closed plumbing system, which most modern homes have because of a backflow preventer or pressure-reducing valve, that extra volume has nowhere to go. The pressure pushes back on your tank, fittings, and valves.
An expansion tank gives that pressure a place to absorb, which protects the water heater and your pipes from early failure. Many local codes now require one, and skipping it can void some manufacturer warranties.
A published guide from a Texas master plumber notes that adding a missing expansion tank on a closed-loop system with a backflow preventer typically runs in the $150 to $300 range to correct. That’s a small fix compared to a tank that fails years early.
Issue 3: No Sediment Trap on the Gas Line
This one is easy to miss and easy to skip. A sediment trap is a short section of pipe that catches debris before it reaches the gas valve.
Code expert Glenn Mathewson, writing for Fine Homebuilding, explains the reason in plain terms (paraphrased): cutting and threading gas pipe leaves metal shavings inside, and gravity alone won’t pull them clear. The trap forces a sharp turn that the gas flows around but heavier debris can’t, so it drops out and stays put.
The placement rule matters too. Per ICC requirements, the sediment trap must sit downstream of the shutoff valve and as close to the appliance inlet as practical. When it’s installed in the wrong spot, it isn’t doing its job.
Issue 4: Venting, T&P Valve, and Drain Pan Failures
These are the dangerous ones, and they’re worth slowing down for.
- Venting: A gas water heater that isn’t vented correctly can let carbon monoxide build up indoors. Inadequate ventilation is one of the most common code violations technicians find.
- T&P relief valve: The temperature and pressure relief valve is the safety device that prevents a tank from building dangerous pressure. A water heater can fail violently if this is installed or routed incorrectly.
- Drain pan: A missing pan under the tank turns a small leak into thousands of dollars of floor and ceiling damage.
If any of these were skipped on your install, that’s not a cosmetic shortcut. It’s a safety gap.
A real cost worth knowing: The Insurance Institute for Business and Home Safety (IBHS) estimates water heater failure claims cost an average of $4,444 per claim, and water heater failures rank among the top five sources of residential water damage.
Issue 5: Sediment Buildup Made Worse by Hard Water
Even a perfect install can fail early if the drain valve and anode rod aren’t positioned for future maintenance. Sediment that settles on the tank floor coats the heating element, drops efficiency, and shortens the tank’s life. That’s also the source of the popping and rumbling sounds people ask us about.
Water hardness plays a big role here. The Water Quality Association (WQA) scale puts soft water at 0 to 3.5 grains per gallon, moderate at 3.5 to 7.0, hard at 7.0 to 10.5, and very hard above 10.5 (1 grain per gallon is about 17.1 ppm).
Tennessee water is generally soft to moderately hard, with a state average near 99 ppm. For comparison, Memphis sits around 55 ppm and Nashville around 79 ppm. But private wells, which are common in rural parts of West Tennessee, often run much harder because untreated groundwater dissolves calcium and magnesium. Around 85% of U.S. homes have some level of hard water.
Because hardness changes by exact location and source, we recommend a professional water test rather than guessing. It tells us how often your tank really needs flushing and whether filtration makes sense for your home.
The 2025 Water Heater Law Changes Most Sites Got Wrong
A lot of plumbing pages still have outdated rules posted. There was a major split in 2025, and the rules now run on three separate tracks. Here’s how they actually stand.
| Water Heater Type | Current Rule Status | Key Date |
| Gas tankless (instantaneous) | Efficiency rule was repealed; DOE withdrew it and cannot reissue a similar rule without new law | Withdrawn May 20, 2025 |
| Electric storage over 35 gallons | Still required to move to heat pump technology | Takes effect May 6, 2029 |
| Commercial gas water heaters | Only high-efficiency condensing units can be made or imported | On and after Oct. 6, 2026 |
A few details behind the table:
- On May 9, 2025, the gas tankless efficiency rule was nullified by Congress, and the DOE withdrew it one day before it was set to take effect.
- The federal 25C tax credit for heat pump water heaters expired December 31, 2025. It had covered 30% of qualifying costs up to a $2,000 ceiling. Units placed in service on or before that date can still be claimed on a 2025 return. Nothing installed in 2026 qualifies.
So if you’ve seen conflicting answers to “do I have to buy a heat pump now,” here’s the short version: no, the gas tankless rule is dead, the electric storage change isn’t until 2029, and the heat pump tax credit is gone.
Why an Unlicensed or DIY Install Can Backfire
We’re not here to scare anyone. We just want you to see the facts before deciding who does the work.
- Some areas require a registered master plumber to pull the permit, meaning homeowners can’t self-permit a replacement even on a home they own and live in (the City of Houston works this way).
- Insurance adjusters check permit status when a water heater causes damage. If an unpermitted install floods a home, the insurer has grounds to deny the claim. Houston’s investigation fee for unpermitted work starts at $333.42 or double the permit fee, with possible fines up to $2,500.
- Most standard homeowners policies exclude normal wear and tear. Insurers generally won’t pay for failures tied to age, rust, or corrosion over an 8 to 12 year lifespan. If a unit failed because of age or neglect, the whole claim, including the water damage, is likely denied.
Permit costs and fines are local, so confirm your own county’s rules with a licensed local plumber. The Houston figures are just an example of how this plays out.
Here’s the bigger picture on timing. IBHS reports the average age of a failed water heater is 10.7 years, and by year 12, nearly 3 in 4 have failed. About 69% of failures come from a slow leak or sudden burst. Yet fewer than 20% of homeowners do basic upkeep like checking hoses or flushing the tank (Triple-I/Munich Re survey). Water heating also accounts for roughly 13% of a home’s energy use (DOE), so an efficient, well-installed unit pays you back every month.
Not sure if your install was done right? If your water heater is older than 8 years or was swapped without a permit, a quick inspection now is far cheaper than a denied claim later. Call Tennessee’s Choice Plumbing and we’ll check it.
Our Pre-Install Verification Checklist
Over years of fixing other people’s installs, we built a simple routine our crew runs on every water heater job. We call it the Tennessee’s Choice Pre-Install Verification, and it covers the five failure points above:
- Load sizing check so the tank matches your real hot water demand.
- Closed-system and expansion tank verification to protect your pipes from pressure.
- Gas-line sediment trap placed downstream of the shutoff and close to the inlet.
- T&P valve, venting, and drain pan compliance for safety.
- Water hardness reading so we know your flushing schedule.
Running the same checklist every time is how we keep installs out of the “issues we see” pile.
Frequently Asked Questions
Do I need a permit to replace a water heater, or can I do it myself? Most areas require a permit, and some only let a licensed master plumber pull it. Rules change by county, so confirm with a local plumber before you start. Skipping the permit can put a future insurance claim at risk.
Will my homeowner’s insurance deny a claim if a licensed plumber didn’t install the heater? It can. Adjusters check permit status after water damage, and an unpermitted or improper install gives the insurer grounds to deny. Wear-and-tear failures on older tanks are also commonly excluded.
Why is my new water heater already making popping or rumbling noises? That’s usually sediment settling on the tank floor and heating element, often a sign the drain valve wasn’t set up for easy flushing or your water is harder than expected. A flush and a water test will tell us more.
Do I have to buy a heat pump water heater now? No. The gas tankless rule was repealed in 2025, and the electric storage requirement for units over 35 gallons doesn’t take effect until May 6, 2029. The federal heat pump tax credit ended December 31, 2025.
Why does a water heater need an expansion tank? In a closed system, heated water expands with nowhere to go, which raises pressure on the tank and pipes. An expansion tank absorbs that pressure and helps the unit last longer. Many codes now require one.
How long does a water heater last before it fails? The average failed unit is about 10.7 years old, and nearly 3 in 4 have failed by year 12 (IBHS). Regular flushing and an anode rod check help you reach the upper end of that range.
Get Your Water Heater Installed Right the First Time
A water heater is only as good as the install around it. The five issues above are common, and every one of them is preventable with a licensed, careful job. Our team serves Jackson, Milan, Whitway, Idlewild, West, Medina, Humboldt, Gibson, Three Way, Martin, Dresden, Union City, Gleason, McKenzie, Paris, Buchanan, Greenfield, and Kenton, and we treat your home like our own.
Whether you need a new install, a second look at a recent swap, or one of our broader residential plumbing services, we’ll do it right the first time. Reach out to Tennessee’s Choice Plumbing for a quote or an honest inspection.