EcoSmart Water Heater Leaking

Common Symptoms

• Water dripping from the bottom of the EcoSmart unit
• Visible water staining or mineral deposits on the unit's exterior
• Water dripping from the pressure relief valve discharge pipe
• Moisture at the inlet or outlet pipe connections
• Water pooling on the floor under the unit
• SMARTHEAT: water dripping from the barb fitting connections

Most Likely Causes

1. 1

   Pressure Relief Valve Dripping (ECO Series)

   EcoSmart ECO units include a pressure relief valve rated at 150 PSI. In a closed plumbing system (one-way check valve or pressure regulator on the supply), thermal expansion can cause pressure to creep above the T&P valve's set point during heating cycles, causing intermittent dripping. An expansion tank on the cold water supply line eliminates thermal expansion pressure buildup. If the T&P valve drips continuously or discharges in full flow, the valve itself may have failed and needs replacement.

2. 2

   Inlet/Outlet Union Connection Leak (ECO Series)

   The ECO units connect to supply and hot water piping via threaded union fittings. These connections can develop slow seepage if the original installation used Teflon tape alone without pipe thread sealant (pipe dope). Tightening the union nut can sometimes stop a minor seep; if the threads are damaged or the seep continues, the fitting must be disassembled, cleaned, and re-sealed with both Teflon tape and pipe dope.

3. 3

   Heating Element O-Ring Leak (ECO Series)

   The copper heating elements are sealed into the ECO unit's heating chamber with a proprietary O-ring. Over time, heat cycling and hard water cause O-ring degradation. A leak at the element flange indicates a failed O-ring. IMPORTANT: only the O-ring included with the genuine EcoSmart element replacement kit (model-specific) should be used — generic O-rings of the same nominal size will not correctly seal the proprietary element thread profile and will continue to leak.

4. 4

   Chamber Seal Leak from Scale Perforation (ECO Series)

   In severe hard water areas, scale accumulation can pit and perforate the copper heating chamber walls. Water seeping from the body of the unit (not from a fitting or the T&P valve) indicates chamber wall corrosion. This condition requires full element replacement and, if the chamber wall is perforated, replacement of the unit.

5. 5

   Water Flow Sensor O-Ring Leak (ECO Series)

   The flow sensor that detects water movement through the ECO unit is sealed with O-rings. These can degrade and cause a slow drip from the flow sensor port, typically visible as moisture near the cold water inlet section of the unit.

6. 6

   Inlet/Outlet Barb Fitting Leak (SMARTHEAT Series)

   SMARTHEAT point-of-use units connect to supply and discharge lines via plastic barb fittings. Barb fitting leaks are caused by over-tightening (cracking the fitting), under-tightening, or degraded tubing compression. Inspect the barb connections and replace the fitting or tubing as needed.

Quick DIY Checks

1. 1Step 1 — SAFETY FIRST — turn off all dedicated breakers: before touching any part of the EcoSmart unit, turn off all dedicated breakers for the unit at the main electrical panel. ECO 36 units have 3 dedicated 40A breakers — turn off all of them. Use a non-contact voltage tester on the wiring inside the unit to confirm no voltage before proceeding. Water and 240V is a lethal combination.
2. 2Step 2 — Identify the leak source: dry the exterior of the unit thoroughly with a towel. Restore cold water supply but keep breakers off. Wait 2–3 minutes and observe where water first appears. Key locations to check: top of unit (T&P valve discharge tube or inlet/outlet union connections); element flange area (O-ring leak); flow sensor port area (flow sensor O-ring); body of unit (chamber wall — serious); barb fittings at inlet/outlet for SMARTHEAT units.
3. 3Step 3 — T&P valve dripping: if water drips from the pressure relief valve discharge pipe, test the valve by lifting the test lever briefly — water should flow and then stop cleanly when released. A T&P valve that doesn't stop dripping after testing has debris in the seat and needs replacement. Measure supply pressure with a water pressure gauge — if supply pressure exceeds 80 PSI or the system is 'closed' (check valve or pressure regulator present), install an expansion tank on the cold water supply. A Watts ET-15 or equivalent is appropriate for most ECO installations.

Repair vs Replace

Recommended Tools & Parts

• EcoSmart Replacement Heating Element Kit (with O-ring)

  Genuine EcoSmart replacement element kit including the proprietary copper element and correct O-ring for your model. The O-ring is model-specific — do NOT substitute a generic O-ring. Order by model number (e.g., ECO 27 E-01 kit).

  $80–$150

  Buy on Amazon →

• Watts ET-15 Thermal Expansion Tank

  Thermal expansion tank for closed plumbing systems. Prevents T&P valve from dripping due to thermal expansion pressure buildup. Install on cold water supply line near the water heater. Sized for residential tankless water heater applications.

  $30–$60

  Buy on Amazon →

• Pressure Relief Valve (150 PSI Rated)

  Replacement T&P valve for EcoSmart ECO units, rated at 150 PSI. Required when the existing valve drips continuously or fails to reseat after testing. Match the 150 PSI rating specified on EcoSmart ECO data labels.

  $15–$30

  Buy on Amazon →

• Pipe Thread Sealant (Pipe Dope) + Teflon Tape

  Combination of PTFE Teflon tape and pipe thread sealant (pipe dope) for sealing threaded union connections on EcoSmart ECO units. Teflon tape alone is insufficient for water-tight sealing under pressure cycling — use both.

  $8–$15

  Buy on Amazon →

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

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