Before a licensed plumber ever lifts a tool, they are trained on one of the most critical safety issues in plumbing: hot water temperature. Industry standards clearly state that a client’s water temperature should never be set above 120°F. This is common knowledge for trained professionals, though often overlooked by the untrained. Manufacturers of both tank and tankless water heaters reinforce this standard in their installation manuals, training programs, warranty documents, and the numerous warning labels mounted directly on the equipment. These requirements exist to protect homeowners from injury and manufacturers from liability.
The Consequences of Excessive Water Temperature
Water temperatures above 120°F pose serious risks, including:
- Scalding injuries to occupants
- Premature failure of plumbing systems, including PEX, CPVC, PVC piping causing flooding to home
- Damage to tankless heaters, Tank type heaters, faucets etc causing flooding to home
- Damage to flexible water supply lines, ice maker tubing, and washing machine hoses causing flooding bro home
PEX piping does not last indefinitely. Manufacturer warranties typically range from 10 to 25 years, provided specific conditions are met. Nearly all warranties exclude failures caused by:
• Water temperatures exceeding 120°F
• Water pressure above 80 PSI
• Recirculation pumps operating continuously (24/7) PEX piping needs time to COOL or REST.
PEX storage considerations:
We only purchase PEX piping stored indoors….
Additionally, all plastic piping is vulnerable to UV exposure. Proper contractors verify that materials were not stored outdoors or exposed to sunlight prior to installation.
Note from our UL laboratory Scientist pertaining to plastic piping stored outdoors:
Nick- You are exactly right! The only way to protect plastic materials from sunlight is to add 5% carbon black. That is why AT&T and all other manufacturers who make telecom gear make it black. White materials (like PVC and PE) use titanium dioxide and calcium carbonate fillers to protect (and cheapen) the plastics. It has little benefit for ultraviolet light exposure. Even PEX is vulnerable if not stored properly!! Your TEAM knows this and that is why you guys are so great.
The perfect storm or PEX Trifecta of Pinhole Leaks
Pinhole leaks most commonly occur when all three of the following conditions are present:
1. Incoming water pressure exceeding 80 PSI
2. Water temperature above 120°F
3. A recirculation pump running continuously
When these conditions exist simultaneously, widespread piping failure is almost inevitable and irreversible!
What You Can Do Now to Limit Damage
1. Set water temperature to 120°F (maximum).
2. UNPLUG recirculation pump when not at home. If piping damages from the trifecta try allowing natural hot water delivery, or reduce pump run time significantly.
3. Install and maintain a pressure regulating valve (PRV) buy test gauge and check pressure on annual basis
4. Turn off main water to home EVERYTIME NO one is home especially on long trips
5. Buy a Water cop / wifi application installed by licensed plumber
About Pressure valves
• Average PRV lifespan is 8–10 years for quality valves
• Inspect regularly for leaks
• Confirm quality features (brass body, internal strainer)
• Verify proper installation (horizontal vs. vertical orientation)
Poor-quality valves or improper installation can reduce lifespan to as little as 2–4 years.
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Electrical Concerns and Pinhole Leaks
If your home is transitioning from copper piping to PEX, a licensed electrician must verify proper grounding and bonding. Removing copper without addressing grounding can create serious electrical and plumbing issues.
In Cobb County, the leading causes of copper pinhole leaks are:
• Electrolysis
• Improper electrical grounding and bonding
• Excessive water pressure above 80 psi, which accelerates corrosion
– Water temps above 120 degrees
– Recirculating pump running 24/7
For over 80 years, homes commonly used copper water piping as part of the electrical grounding system. However, many older homes now have plastic underground water lines, which are non-conductive. When grounding paths are interrupted, stray electrical currents seek alternate routes—often through metallic plumbing components.
Consider this sequence:
• Electrically charged water containing iron flows through copper piping
• Water is heated in a steel tank
• The heater contains a magnesium sacrificial anode rod
This combination effectively creates a battery-like environment, accelerating corrosion throughout the plumbing system.
Electrolysis Explained
Electrolysis occurs when dissimilar metals are present, such as copper connected to galvanized steel. Even a single galvanized nipple or improperly bonded ground wire can initiate corrosion.
Additionally, if the sacrificial anode inside the water heater is fully depleted and not replaced, corrosion shifts from the anode to the copper piping itself—often resulting in pinhole leaks.
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Water Quality: Separating Fact from Fiction
In Cobb County, water quality is not the cause of pinhole leaks. Claims to the contrary are inaccurate.
Cobb County publishes an annual water quality report and treats its water with calcium hydroxide (lime). This process:
• Improves taste
• Reduces corrosivity
• Forms a protective calcium carbonate coating inside copper pipes
This protective barrier significantly limits corrosion. In fact, Cobb County water is among the best-treated municipal supplies in the state.
While acidic water can cause pinhole leaks in other regions, this is not applicable in Cobb County.
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Green Stains on Copper Fittings
Green or bluish stains around copper fittings—especially if slimy—are often caused by excess flux not wiped off during soldering. This is a workmanship issue, not a system failure. The residue can be cleaned with a cloth and a warm water/TSP solution.
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Final Thoughts
Homeowners experiencing pinhole leaks in copper, CPVC, PEX, or older poly piping should consult a licensed master plumber with specific expertise in these issues. Not all plumbers specialize in every aspect of the trade.
Choosing the right professional—not simply the lowest bidder—will save time, reduce frustration, and prevent costly repeat failures. Just as you wouldn’t ask a foot doctor to treat a heart condition, proper diagnosis requires the right specialist.
Nick Marine / Tony Little
Marine Plumbing Service, Inc
“A few good Plumbers”