or… “Is My Quickly Prepared Spaghetti Killing my Family”
I expected Dr. Google to answer this quickly, but have had no such luck.
I have heard that cooking and drinking from the hot water tap in your house is dangerous. I believe that the first time I heard it was in regard to mixing baby formula with hot water because of the risk of lead contamination. But I have also heard about the dangers of corrosion, leeching metals, and the mysterious sludge at the bottom of water heaters.
Is this a real health concern? The only places that I have seen this posted on the internet where FAQs of companies that sell water purification systems.
No. The water heater is connected to the cold water line. If there was a health concern there would be a requirement for a backflow prevention device on the water heater to prevent the contaminated hot water from mixing with the cold water (which you do drink).
That being said, there is the possibility of minerals precipitating out of solution, expecially with hard water. That would be the ‘sludge’ at the bottom of the heater. It wouldn’t be a health problem, but it may affect the taste of the water. Hot water can hold less dissolved gas than cold water, so that might also affect the taste. Finally, under some conditions a bacteria can grow in a hot water tank and these produce a sulfur smell in the water. This is usually due to the presence of a mangnesium anode in the tank, which is there to prevent tank corrosion. Again, not harmful, but the hot water stinks of sulfur.
Actually modern water heaters do have an anti syphon device, but it’s to prevent the heater from damage rather than to prevent any cross contamination w/ the cold water.
Heating water will raise the pH making the water more corrosive then it is when cold. In some cases the water becomes acidic enough to desolve copper and solder joints into the water. Copper isn’t all that healthy for people and if it is an older home the solder may contain lead.
Overal I wouldn’t worry about hot water being unhealthy. If you are getting blueish or greenish staining I might be more concerned. More so for the health of your pipes then peoples personaly health(you can injest a good amount of copper without negative effects). Turning down the temperature on the hot water heater can help prevent it from becoming too corosive.
With infants I would recomend using bottled water. That eliminates the risk of lead or heavy metals that can be very dangerous to them.
The water heater acts as a filter of sorts. Where do you suppose the sludge at the bottom of the water tank came from? It has been removed from the cold feed water by the heating tank. So it’s the cold water tap that is really rich in sedimenty goodness. The only thing a water heater adds to cold water is energy.
I don’t see how bacteria are going to live in scalding hot water. And if there is a type of bug that lives in that environment, it’s not going to be happy at human body temperature.
I have seen inside water heaters. It is not pretty. As mentioned in other post’s, there is aluminum in a high percentage of water heaters from the anode rod. If for no other reason I would not consume the water from a water heater unless it was filtered first. You can’t boil aluminum out so filtering is the only option.
Let’s say that is not a good enough reason for you. How about the bacteria that is growing in most water heaters. There are a number of types of bacteria in water heaters operated at or below 130 degrees. The worst is the Legionella bacterium. It is estimated to be in up to 25 percent of American water heaters. It can cause severe and sometimes fatal pnemonia. People get the pnemonia by breathing the vapors from the hot water waen they are running hot water in a sink or taking a shower. Like almost any bacteria it cannot grow above 140 degrees. I hope most of you are remember from your health classes back in high school that food safe temperatures (where the bacteria won’t grow and be dangerous) are less than 40 degrees and more than 140 degrees.
Now that being said, 140 degrees is very hot and will cause scalding. There are solutions to that that are not too expensive to install in most cases. The easiest is a thermostatic mixing vavle that connects to the hot and cold pipes at the top of the water heater. Honeywell makes a nice one that can be installed by a plumber in just a few minutes. Usually $250. to $300 installed in my area. This will increase your water heateing bill and give you more hot water to work with.
The best solution to all of the problems with American water heaters is to install a ‘tankless’ or ‘Hybrid’ water heater. They are substantially more efficient (up to 98%) smaller, have a longer lifespan. Nothing grows in them because the plumbing is just copper and stainless steel and they have a high flow rate. No anode rod, no rusting and substantially more efficient than the tank type used pretty much exclusively in North America.
How do you know that every house in the US has the same type of water heater?
Because here, most residental homes with flowing hot water have a huge boiler downstairs. Because the water will sit there for a long time, two potential problems are either bacteria (Legionelles) and chemicals added to combat bacteria and chalk deposits (our water is very hard, and a boiler full of chalk will use more energy).
In older houses, when there is no central warm water, people will install their own system, which can be either a small boiler - with the problems of above or not, depending on personal use - or a flow heater. The disadvantage of a flow heater is that it takes some time to get the water hot, but once it is hot, there is no residue or other problems, since it’s cold water being heated that instant.
Therefore, unless you have a personal water system, or know exactly that the water system used is safe, it’s recommended here to use cold water and heat it in a kettle for drinking and cooking.
If you worry about lead in your hot water, why wouldn’t the lead also affect the cold water?
Straight dope? Yes, water drawn from a hot tap may be higher pH than the cold due to outgassing. Raising the pH reduces the acidity. However, the outgassing may not happen until the water is drawn and the pressure lowered. Back flow? Yes as water is heated, it expands and the excess has to go somewhere. Current codes require backflow preventers at the meter for public water systems. That in turn requires an expansion tank before the water heater. Thus heated water doesn’t make it back to the cold in such systems. Water that is forced out of a hot water tank before fully heated should be less of a problem than water that sets in a tank. Note the surface to volume ratio of a tank compared to a pipe. The worst water should be what has set hot in a pipe between the tank and tap. Tankless heaters do nothing to change that problem. Their muchly hyped ‘‘instant’’ hot water is at the outlet of the heater, not the tap.
Both hot and cold water extract metal and other components out of any container they are in including metal and non metal pipes. Hot water extracts more.
There are systems that use a coil in the space heating system to heat hot water. However, I doubt they are common.
I don’t fully trust what the federal government tells me, but the advice that Twoflowers posted in #4 sounds likely. I always start with water out of the cold tap for cooking and drinking. Now, how much is my water contaminated by whatever device I use to heat it? At least it shouldn’t set in lead soldered joints long.
