Water heaters fail in two modes: slow and sudden. Slow failures look like declining hot-water duration over a few weeks, a popping or rumbling sound from the tank, or rust-tinted hot water at the tap. Sudden failures are wet floors. Both end the same way — a new tank, or a tankless conversion — but the slow-failure customer has the luxury of choosing on Tuesday afternoon while the sudden-failure customer is calling us from a Best Buy parking lot at 11pm.
Mercer Plumbing stocks 40-gallon and 50-gallon gas and electric tanks on Truck 4. Most inside-Charlotte tank failures get a same-day swap-out. Tankless installs are scheduled because they require permit pulls, a longer install window (4-6 hours), and often a gas-line upgrade. Hector handles all our tankless work and carries current Navien, Rinnai, and Rheem manufacturer certifications.
Tank vs. tankless — which is right for me?
Tank is simpler, cheaper to install ($1,840 for a standard 50-gallon), and right for households with steady moderate demand. Tankless is more expensive up front but lasts twice as long, never runs out of hot water, and cuts water-heating energy use 20-30%. Most households we serve in Charlotte's older neighborhoods (Plaza Midwood, Dilworth, Myers Park, NoDa) end up sticking with tank for replacement-on-failure. Most households we serve in Ballantyne, Eastover, and the larger newer-build homes go tankless on replacement.
The decision is mostly about three things: how many people live in the house, how often more than one hot fixture runs simultaneously, and how long you plan to stay. Tankless makes the most sense for households of 3+ where two showers run at the same time, or homes planning to stay 10+ years. Tank makes the most sense for everyone else.
If you fix it before you replace it
Tanks under ten years old are usually worth repairing, not replacing. We diagnose, we tell you the repair cost, and we let you decide. We do not quote new tanks reflexively when a thermostat or anode rod will solve the problem for a fifth the price.
Common repairs: thermostat replacement ($180-$240), thermocouple ($165), heating element ($195), anode rod ($235), dip tube ($185), T&P valve ($145). These take 30-60 minutes on the truck. The diagnostic is $69 and applies to the repair.
| Standard 50-gallon tank install (gas or electric) | $1,840 |
| 40-gallon tank install | $1,640 |
| 75-gallon tank install | $2,485 |
| Tankless install (Navien / Rinnai / Rheem) | $4,200–$5,800 |
| Repair diagnostic (applied to repair) | $69 |
| Annual flush + anode inspection | $145 |
All installs include permit pull, code-compliant gas/electric connection, and T&P discharge piping.
"If your tank is under ten years old, the answer is usually a thermostat or an anode rod. We will not quote you a $1,840 new tank when you needed a $180 part." — Hector Vasquez, water-heater lead
Charlotte water hardness and tank life
The Catawba River supplies most of Charlotte's tap water. Hardness runs roughly 40 mg/L — moderate, not severe. Severe hardness (anything above 120) is what shortens tank life dramatically. At Charlotte levels, a properly-maintained tank should hit its 10-12 year nameplate life, and an annual flush extends it 2-3 years beyond that.
An annual flush is the single best maintenance investment a tank water heater owner can make in Charlotte. We do it for $145, including a visual inspection of the anode rod and replacement recommendation if it's depleted (anodes usually need replacing every 4-5 years and they extend tank life dramatically when replaced on schedule). We do not sell maintenance plans for it. Schedule it yourself when you remember.
Tankless · what you should know before you decide
Tankless heaters are not a one-for-one swap. They need a larger gas line (3/4" minimum, 1" for high-demand units), a dedicated condensate drain (the high-efficiency units produce acidic condensate that has to go somewhere), proper venting (PVC for condensing units, stainless for non-condensing), and a service interval (annual descaling, especially in any home with above-average hardness). They also cost more to repair than tanks — the units are more complex and parts are more expensive.
The benefits: 20+ year service life, infinite hot water (you cannot run out), 20-30% energy savings on water heating, and significant garage/utility-room space recovery (the unit hangs on the wall). For the right household, they are a clear win. For a single-person household with one bathroom, they're overkill.