Lochinvar Water Heater Leaking: Find the Source and Fix It

Common Symptoms

• Water puddle on the floor directly under the water heater
• Water dripping or running down the side of the Lochinvar unit
• Water seeping from the drain valve at the bottom of the tank
• Water dripping from the T&P (temperature and pressure) relief valve or its discharge pipe
• Moisture or corrosion stain at the top of the tank around the cold inlet or hot outlet fittings
• Water seeping around the heating element mounting flange (Lochinvar electric models only)
• Corrosion or rust stain at the anode rod hex port on top of the tank
• Rust-colored water in the drain or floor drain below the unit

Most Likely Causes

1. 1

   Drain Valve Dripping (Most Common Minor Leak)

   The drain valve at the bottom of the Lochinvar tank — typically a plastic or brass ball valve or hose bibb — is the most common leak source. Plastic drain valves on residential models are prone to a slow drip from the valve stem after years of infrequent use. A drain valve that was opened for flushing and not fully closed may also seep at the packing. First attempt: tighten the valve packing nut slightly or seat it firmly closed. If the drip persists, the drain valve must be replaced: a Watts 3/4-inch brass ball drain valve ($8–$15) is the standard replacement. Drain valve replacement requires a full tank drain and temporary water shutoff.

2. 2

   T&P Relief Valve Dripping or Discharging

   The temperature and pressure relief (T&P) valve on a Lochinvar water heater is a critical safety device — it opens to discharge water when tank pressure or temperature exceeds safe limits. A T&P valve that drips continuously from its discharge pipe can mean: (a) the valve itself is weeping due to a worn seat or scale buildup — test by gently lifting the lever to flush any debris, but do not lift and hold for more than 5 seconds; (b) high system pressure — if your home water pressure exceeds 80 PSI or there is thermal expansion in a closed-loop system, the valve opens in response to normal pressure spikes. Install a pressure gauge and, if needed, an expansion tank. A T&P valve that has been tested with the lever or is over 6 years old should be replaced as a precaution after any leak event. Standard replacement: Watts 100XL 3/4-inch T&P valve.

3. 3

   Heat Trap Fitting or Nipple Leak at Tank Top

   Lochinvar water heaters use heat trap nipples — dielectric or plastic-insert fittings — at the cold water inlet and hot water outlet connections at the top of the tank. These fittings can develop leaks at the threaded connection after years of thermal cycling and corrosion, or if the fittings were installed without adequate thread sealant. Moisture or rust staining at the top of the tank near the plumbing connections usually indicates a heat trap fitting leak rather than tank failure. Replace leaking heat trap nipples with Watts LF38 dielectric heat trap nipple assemblies. Apply PTFE (Teflon) tape on all threads before reassembly. Replacement requires shutting off the cold water supply to the heater.

4. 4

   Heating Element Gasket Leak (Lochinvar Electric Models)

   Lochinvar electric tank water heaters have two screw-in heating elements — upper and lower — each sealed to the tank by a rubber gasket. Over time the gasket compresses, hardens, and begins seeping water around the element flange. A weeping element gasket typically produces a slow drip from the side of the tank at the element access panel height. Tightening the element flange is not possible on screw-in elements — the element must be removed, the old gasket replaced (or the element replaced with a new Camco 02162 kit that includes a fresh gasket), and the element reinstalled and torqued to specification. Full tank drain is required before element removal.

5. 5

   Anode Rod Port Leak

   The magnesium or aluminum sacrificial anode rod screws into a hex port at the top of the Lochinvar tank, protecting the steel tank interior from corrosion. If the anode rod was removed (for flushing or inspection) and reinstalled without adequate PTFE tape on the threads, or if the rod has fully dissolved leaving a compromised fitting, the port can weep. Moisture or rust at the hex fitting on top of the tank (typically 1 1/16-inch hex) suggests an anode rod port leak. Remove the rod, inspect the threads, apply three wraps of PTFE tape, and reinstall. Use a Corro-Protec CP-R powered anode rod or a magnesium anode rod (Lochinvar part or Rheem SP11702 cross-compatible).

6. 6

   Tank Body Corrosion and Liner Failure

   A Lochinvar tank that has exceeded its service life (typically 8–15 years depending on water quality and anode rod maintenance) can develop internal corrosion that penetrates the tank liner, causing a slow seep through the outer jacket. Tank body leaks typically appear as rust staining or moisture on the bottom insulation jacket or at floor level around the unit base. Unlike component leaks, a tank body leak cannot be repaired — the unit must be replaced. Confirm the leak is from the tank body and not a component: dry the entire exterior of the unit, place paper towels at all component locations, and inspect after 2–4 hours to identify the wet area.

Quick DIY Checks

1. 1Step 1 — Dry the tank exterior and identify the exact leak source: before touching any fittings, dry the entire exterior of the Lochinvar water heater with towels, paying special attention to the top (hot/cold plumbing connections), the T&P discharge pipe connection, the sides (element access panels on electric models), and the base. Place paper towels around the drain valve, at each access panel seam, and under the T&P discharge pipe outlet. Wait 30–60 minutes and check each paper towel for moisture — the wet paper towel identifies the leak zone. This prevents misdiagnosis and ordering the wrong parts.
2. 2Step 2 — Inspect and tighten the drain valve: locate the drain valve at the bottom of the Lochinvar tank. If the valve is plastic and dripping from the valve stem, attempt to seat it fully closed — turn clockwise firmly. If a slow drip persists, wrap the valve stem packing nut with a single layer of PTFE tape and retighten the nut slightly. If the valve body is cracked or the drip continues, drain the tank and replace the drain valve: shut off cold water supply to the heater, connect a garden hose, open the drain valve fully to drain the tank, then use a pipe wrench to unscrew the old valve and install a Watts 3/4-inch brass ball drain valve with PTFE tape on the threads. Torque to snug-tight, refill the tank, and check for leaks.
3. 3Step 3 — Check the T&P relief valve and discharge pipe: locate the T&P valve — it is typically mounted on the side of the Lochinvar tank near the top, with a discharge pipe running toward the floor or a floor drain. If water is dripping from the end of the discharge pipe, the T&P valve is opening. Check the home water supply pressure with a pressure gauge at any hose bibb or laundry connection — if pressure exceeds 80 PSI, install a pressure reducing valve and an expansion tank. Test the T&P valve only if it has never been tested: lift the lever briefly (1–2 seconds) to flush any mineral debris from the seat, then release — water should stop immediately. If the T&P valve continues to drip after the flush test, it must be replaced (Watts 100XL 3/4-inch T&P valve, set to 150 PSI/210°F). T&P valve replacement requires draining the tank below the valve inlet.

1. 4Step 4 — Inspect heat trap nipples and top plumbing connections: look at the cold inlet and hot outlet connections at the top of the Lochinvar tank. If you see moisture, mineral deposits, or rust staining around either fitting, a heat trap nipple is leaking at the threads. Shut off cold water supply to the heater. If the heater is gas, turn the gas control to PILOT or OFF. Drain down slightly to reduce pressure. Wrap the leaking fitting with plumbing tape and carefully unscrew — counterclockwise. Inspect the male threads on the tank nipple for corrosion. Clean with a wire brush. Apply three wraps of PTFE tape to the threads. Install a new Watts LF38 dielectric heat trap nipple (or the same heat trap removed if undamaged) and tighten to snug-tight plus 1.5 turns. Do not over-tighten — cast threads can crack. Restore water supply and check.
2. 5Step 5 — Inspect heating element gaskets (Lochinvar electric models only): turn off the 240V circuit breaker for the water heater. Remove the upper and lower access panels (2–4 screws each) and fold back the insulation. Look for moisture or white mineral deposits at the element mounting flange on either the upper or lower element. If a seep is confirmed, the element gasket must be replaced: drain the tank completely (connect a garden hose to the drain valve, open a hot water tap to break vacuum). Use a 1.5-inch element socket to unscrew the element. Remove and discard the old rubber gasket. Install a Camco 02162 replacement element kit (includes a new gasket). Torque to 20 ft-lb (snug-tight plus 1/4 turn with a socket wrench). Refill the tank completely before restoring 240V power — never energize heating elements with air in the tank.
3. 6Step 6 — Check the anode rod port for thread seepage: on top of the Lochinvar tank, locate the hex fitting for the anode rod (1 1/16-inch hex, typically covered by the jacket or a plastic cap). If moisture or rust originates at this fitting, the anode rod thread seal has failed. Shut off cold water and relieve pressure. Using a 1 1/16-inch socket and breaker bar, remove the anode rod. Inspect the threads — clean with a wire brush. Apply three wraps of PTFE tape and reinstall. Tighten firmly to at least 40 ft-lb (the fitting is deep in the tank and requires significant torque). Restore water supply and check. If the rod is depleted (less than 1/2-inch core remaining), replace with a new anode rod: Corro-Protec CP-R powered anode or a magnesium rod (Lochinvar OEM or Rheem SP11702 cross-compatible).
4. 7Step 7 — Evaluate for tank body corrosion: if all component locations are dry but water is still present at floor level, inspect the bottom insulation jacket and base of the tank for rust, damp insulation, or soft spots. Tank base leaks where the insulation is wet and rusty indicate internal liner failure — the tank cannot be repaired and must be replaced. To confirm: dry all surfaces, run the unit normally for 2 hours, and return to inspect. If water reappears only at the base with no identifiable component source above, the tank liner has failed. Begin planning for a replacement Lochinvar or equivalent unit.

Repair vs Replace

Recommended Tools & Parts

• Watts 3/4-Inch Brass Ball Drain Valve

  Replacement brass ball drain valve for Lochinvar water heaters. Use to replace failed, cracked, or continuously dripping plastic drain valves. Install with PTFE tape. Standard 3/4-inch MHT (male hose thread) connection.

  $8–$15

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• Watts 100XL 3/4-Inch T&P Relief Valve

  Replacement temperature and pressure relief valve for Lochinvar residential water heaters. 150 PSI / 210°F rating. Replace if the existing valve is over 6 years old or continues to drip after flushing the seat. Must match BTU rating of the heater.

  $15–$40

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• Watts LF38 Dielectric Heat Trap Nipple

  Replacement dielectric heat trap nipple for the cold inlet or hot outlet connections at the top of Lochinvar tank water heaters. Prevents galvanic corrosion between dissimilar metals in the plumbing connections. Apply PTFE tape to threads before installation.

  $10–$20

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• Camco 02162 4500W Screw-In Heating Element with Gasket

  Replacement heating element kit for Lochinvar electric tank water heaters. Includes rubber gasket for leak-free element installation. Full tank drain required before removal. 4500W 240V screw-in type.

  $18–$35

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• Corro-Protec CP-R Powered Anode Rod

  Titanium powered anode rod replacement for Lochinvar water heaters. Eliminates rotten egg odor, lasts the life of the tank, and prevents internal corrosion. 1 1/16-inch hex. Replace if OEM magnesium anode is depleted. Apply PTFE tape to threads.

  $45–$70

  Buy on Amazon →

Links are Amazon affiliate links (tag: fixitfastai-20). Prices are estimates.

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