Addressing Bleach Concerns for Your Hot Water Heater in a Travel Trailer

I have received more than a few questions regarding the wisdom of allowing bleach solution into a metal hot water tank in a travel trailer, often prompted by discussions around RV winterization and sanitization videos. Some individuals have expressed genuine concern after viewing other content, while a few have been less courteous in their questioning.

The common sentiment is typically along the lines of, “I appreciate your video, but I disagree with putting bleach into the Hot Water Heater Travel Trailer.” Others mention encountering content creators who assert you should never use bleach in a hot water heater. Addressing the use of diluted household bleach for sanitizing the plumbing system, including the hot water tank, is crucial for maintaining a healthy environment while enjoying your travel trailer adventures.

Pouring household bleach from a bottle into a measuring cup for RV water tank sanitization

Being analytical by nature (a trait from a former career) and noticing that this prohibition wasn’t present in either the RV manufacturer’s water system sanitation guidelines or the water heater manufacturer’s owner’s manual, I decided to delve deeper.

With the assistance of a structural engineer acquaintance from a specific RV forum, I was directed to a metallurgy study focusing on hypochlorite solutions (bleach solutions) and their impact on metal weight loss (corrosion) over time at various dilution levels. While this might seem a bit technical, understanding it is essential when evaluating the actual risk versus the perceived risk of introducing a bleach sanitizing solution into a metal holding tank.

The trade-off in terms of risk is significant: potential corrosive damage to the hot water tank over an extended period versus the immediate health risk posed by not sanitizing the entire RV plumbing system, including the hot water tank. It’s a risk assessment every RV owner undertaking plumbing sanitation, whether in a large fifth wheel or one of the best lightweight travel trailers under 3500 lbs, should be aware of.

Running diluted bleach solution through an RV's plumbing system to sanitize the water lines and hot water heater

Here are the primary assumptions and outcomes derived from the study, applied to this specific issue. They demonstrate why, generally speaking, using a diluted bleach solution in a metal hot water tank for a minimal duration is not considered a critical factor impacting the equipment’s life expectancy.

Understanding the Metallurgy Study

Assumptions

• RV manufacturers typically advise a sanitizing solution comprising 1/4 cup of household bleach per 15 gallons of water. This equates to a dilution ratio of approximately 1 part bleach to 960 parts water, or roughly 1,042 ppm (parts per million). This solution is recommended to remain within the plumbing system for a minimum of three hours to effectively sanitize the system.
• A study published in the India Journal of Chemical Technology (Vol 1, July 1994) provides data on corrosion rates related to chloride levels. According to Table 1 on page 226 of this study, at a similar chloride concentration level, the estimated corrosion rate is approximately 3.32 mpy (thousandths of an inch per year), assuming continuous exposure for one full year (8,760 hours).
• Household bleach contains only about 5% Chloride. While the actual ppm in the diluted solution would be closer to 200 ppm, the study’s findings on mpy rates don’t significantly decrease at this lower concentration. Therefore, to be conservative, we’ll retain the 3.32 mpy corrosion rate as if it applied to a full year’s exposure.

Conclusion and Calculation

Given that the sanitizing solution only remains in the tank for approximately three hours, the exposure duration is dramatically less than the full year (8,760 hours) used in the study’s mpy calculation. We can determine a reduction factor by dividing the exposure time by the total time in a year: (3 hours / 8760 hours) = approximately 0.00034247.

The adjusted corrosion rate for three hours of exposure is calculated by multiplying the annual mpy rate by this reduction factor: 3.32 mpy * 0.00034247 = 0.001137 mpy.

This adjusted rate translates to 1.137 millionths of an inch of corrosion resulting from three hours of exposure to a household bleach solution exceeding 200 ppm.

To put this into perspective, consider the thickness of your hot water tank’s interior metal wall. If it’s, for example, 1/8th of an inch wide, this measures 0.125 inches in decimal form. A corrosion rate of 1.137 millionths of an inch is equivalent to 0.000001137 inches.

To estimate how long it would take, using this method (a three-hour soak once per year) at this dilution level, to corrode 1/8th of an inch of metal, you would divide the tank thickness by the annual corrosion loss: 0.125 inches / 0.000001137 inches per year = approximately 110,619 years. It’s highly improbable your travel trailer or its hot water heater will still be in use by then.

Identifying the Real Risk

According to my structural engineer friend, the primary risk of corrosion to your hot water tank isn’t due to a properly diluted bleach solution used for a very brief interval during periodic sanitization. The more significant danger of corrosion stems from the acidity level of the water left in the tank during typical use. Many individuals, especially those living in a travel trailer or using them regularly, tend to leave water in the hot water tank throughout the camping season and between trips. Few drain the entire plumbing system, including the hot water tank, between short trips (though perhaps it’s a practice we should all consider). Consequently, the risk of leaving acidic water sitting in the tank for prolonged periods poses a greater potential for corrosion. He mentioned that a simple pool water tester can be used to check the pH level of your water source. If the water is acidic, adding baking soda to the tank can help increase the pH.

A six-gallon hot water tank from a Keystone Bullet travel trailer, commonly found in RVs

Conclusion

Hopefully, having read this explanation, you now have a clearer understanding of the reasoning behind this sanitization practice. My personal priority is maintaining a sanitary plumbing system to ensure health and well-being while using my RV, rather than being overly concerned about the long-term (or extremely long-term) effects of minimal corrosion on my hot water tank. The cost and health implications of a single trip to the emergency room far outweigh the potential cost of replacing a hot water tank many times over. This is true whether you own a standard model or a specialized unit like a quad bunk bed travel trailer or a Jayco toy hauler travel trailer.

If you are interested in reviewing the referenced metallurgy paper and learning more, here is the link to the article: http://nopr.niscair.res.in/bitstream/123456789/31207/1/IJCT%201%284%29%20225-229.pdf.

As always, I strongly recommend consulting the specific manuals relevant to your particular RV model and components whenever you perform any service or maintenance tasks.