Can you imagine being scalded to death in a bathtub or whirlpool tub? It happens. Having been involved in a few legal cases where there have been deaths, it is upsetting that all of these deaths could have been avoided.

What is surprising is how many people don’t know the temperature at which they take a bath. Many in the plumbing profession don’t know either. The average bath temperature is between 102 and 104 degrees F.

If you hop in a hotel hot tub and say, “Geez, this is hot!” the water temperature is probably 105 degrees F. Your normal body temperature is 98.6 degrees F. You don’t want to be taking a bath or shower too much hotter than body temperature.

If you don’t trust me on any of these numbers, check for yourself. Take a thermometer into the bathtub, and when the bath feels comfortable, measure the water temperature. You’ll be right in the range that I stated.

Careful Around Hot Water

The relaxation in a whirlpool tub can also be fatal. People have been known to pass out from the heat with the jets still running. Their body temperature continues to rise. I was involved with one case where the person was unconscious in the whirlpool tub. When they removed him, his body temperature was 108 degrees F. He died six hours later.

Whenever your body temperature rises above 105 degrees F, you begin to boil your brain.

Another hazard with hot water in tubs is people or children falling into the tub during the filling operation. Sometimes this involves an individual testing the water and falling in the tub. Other times it is a small child that inadvertently falls into a tub. It doesn’t take long for hot water to scald the skin.

If the tub is initially filled with only hot water, the temperature of that water becomes critical. At 140 degrees F, a person sustains second- and third-degree burns within seconds. If the water is hotter, it becomes even more dangerous.

Anytime the water is in excess of 120 degrees F, burns to the skin occur very rapidly. Below that temperature, there is still the hazard that I have previously identified.

Industry Efforts

The tub filler must be protected by a thermostatic mixing valve that prevents the water from rising above 120 degrees F. The standard that is referenced is ASSE 1070. This standard has been confusing to many. I am often asked if these valves are central thermostatic mixing valves or tub fillers that mount on the tub. The answer is both. The standard allows a central-type valve or an individual-type valve.

You need to be careful in selecting the valve if it is a central thermostatic mixing-type. There also are central thermostatic mixing valves that conform to ASSE 1017. These valves are not acceptable. The difference between the two valves is that an ASSE 1070 valve has a fail-safe feature. If the water rises above the set point, the water shuts off, thus avoiding a scald.

I have listened to some contractors comment that they need to get the tub installed before the new code is fully effective. The concern stated was that these new required valves cost more money and the contractor will lose profit. This is not only short-sighted, but a dumb comment as well.

If you are providing a higher level of safety, the first thing to consider is that you can charge more money because of the slightly higher cost of the installation. But, more importantly, think about the cost of litigation if someone is scalded. Imagine an attorney asking you why you didn’t install the better valve that would have protected the user of the bathtub and/or whirlpool tub. How do you think the jury will feel if you respond that you were concerned with your profit? Everyone in the courtroom will hear “cha-ching” in the background.

Setting The Max

One of the reasons for the maximum temperature of 120 degrees F is due to the possibility that the tub is a cast-iron tub. Cast-iron tubs absorb a lot of heat during the filling operation. Hence, the filling of a cold cast-iron tub significantly lowers the temperature of the water.

Another factor is the addition of water to reheat a tub. If the water is cooling off, users have a tendency to add hot water to increase the temperature. If the water is not hot enough, it will not reheat the tub.

You don’t have to have the setting at the maximum of 120 degrees F. You will find that many contractors set the valve between 110 and 117 degrees F. The reason for this is that it is easy to test with your hand. You cannot hold your hand steady under water above (approximately) 117 degrees F. You will pull your hand away from the water.

One final important factor is the timer in a whirlpool tub. There is a reason that the federal government recommends no more than 15 minutes in a hot tub or spa. After that time, you may pass out and die. So when installing any whirlpool tub, make sure the timer does not exceed 15 minutes. If users want to be in the whirlpool for a longer period of time, let them reset the timer each time.

These are simple rules and requirements to follow to protect your customer. Keep that bathtub and whirlpool tub safe.

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