It seems like you would get pretty nasty germs happily living in our plumbing (especially untreated well water).
I think about the water that can sit for prolonged periods in hot water tanks, stagnant water in dead end sections of the plumbing system (unused outside faucet etc), and the wet oxygen rich environment inside the faucet ends.
Yet you almost never hear about people getting sick from their water🤷🏽♂️
In: 1670
The water that goes into the pipes is very purified, so it contains little/no bacteria or stuff for them to eat.
In theory, there are no leaks along the way. When there is a leak, the contents of the pipe are under pressure, so water leaks out instead of other stuff getting in.
The water only flows one way, so even if the outlet is dirty, the bacteria can’t really make it far back up the pipe before getting flushed back out.
Tap water has bacteria in it, water pipes also often have biofilms that can release bacteria. The important part is its not harmful bacteria, and its fairly dilute. Most of it probably dies when exposed to your stomach acid.
Tap water often contains low levels of microorganisms such as bacteria and amoebae but these are killed by your stomach acid. These microorganisms generally are not considered harmful.
It’s also important to note that your body has more bacteria in it by weight than human cells, and you probably consume bacteria all the time in certain types of food like yogurt, not all bacteria are harmful for you.
Well water is also prone to being contaminated this way, it’s just a fact of our ecosystem.
The human body is setup to tolerate a certain amount of contaminated water because we evolved to drink water from natural sources.
Your local authority constantly monitors the quality of the water and if levels of microorganisms gets too high they will treat the water with low levels of chlorine to kill them off. This is why tap water sometimes has the distinctive pool smell.
The amounts of chlorine they use are so tiny that the water is still perfectly safe to drink, but if you don’t like the smell you can boil the water or use a charcoal filter to get rid of it.
One of the keys is that the water is constantly moving about and our water is sanitized prior to going into the domestic water piping.
In places where water sits, as you mentioned, you *don’t* want drink that water. For example you don’t drink or cook with water from the hot water tap, you use only cold water. Build codes are in place that avoid dead-end piping runs to avoid build up like you’re suggesting. Finally, we have designed our plumbing systems to avoid water being ‘sucked back in’ if it’s dirty, for example, water in a toilet bowl cannot be sucked back up into the domestic water piping if there a problem with water pressure. All of our plumbing devices are designed this way ideally.
finally, to prove your point, the one place where water does sit and sit and sit and sit are fire sprinkler pipes and unlike what you see in action movies when those heads go off the water is anything by clear and pure. It’s dank and stinky and nasty.
Well, for starters tap water is treated with chlorine or chloramine which acts as a disinfectant, killing most bacteria, mold, and anything else in the pipes. Chlorine evaporates quickly, but in the pipes there’s nowhere for it to go so it sticks around. Chloramine stays in the water even longer and is used for longer pipelines.
Second, there’s rarely anything for bacteria to feed off of. The water comes out of a treatment center as more or less sterile and pure. Although there are opportunities for bacteria to get in (don’t look up the insides of water towers – generally clean, but sometimes… not so much), the water remains mostly very clean and pure unless there’s something very wrong and that means there’s nothing to sustain or grow bacteria even if the chlorine wasn’t killing it.
Your water heater is (generally) hot enough and pressured enough to prevent bacteria from growing. Note that this is only true for sealed water heaters. Older style open heaters are *not* safe for consuming the water which is why sinks with a separate tap for hot and cold are common in older homes that may not have been updated, typically in Europe.
At the end of the day, though, tap water is *not* sterile. There’s a reason you’re supposed to boil water before using it for something like a Neti pot, where you pour water through your sinuses. Despite that, the bacteria level is kept very low, and most of what we do with water doesn’t need to be perfectly sterile. Even drinking water straight from the tap is safe because the few pathogens capable of surviving through the water system aren’t going to survive going through your stomach and your immune system (again, unless something is very wrong with the water system). It’s only doing something like flushing the water directly through your vulnerable sinuses that it really becomes dangerous. Pathogens that historically infect water systems, like giardia or cholera do not survive the purification process, aren’t introduced (because we keep our sewers and drinking water separate), and can’t survive the chlorine to get to us.
The purpose of a water tower is not to hold water. It is to create pressure in the pipes causing pressure at the tap/spigot but more importantly so that if a pipe breaks or cracks everything is flowing OUT not in.
The bacteria are minimal, the real danger is lead pipes. Lead is a powerful neurotoxin that causes brain damage. It can also injure other soft tissues and organs, can interfere with the formation of blood, and it can even kill you.
Lead builds up in the body, often over months or years. Even small amounts of lead can cause serious health problems. Children younger than 6 years are especially vulnerable, it can and does severely affect mental and physical development.
*”Why doesn’t water in our pipes get bacteria…”*
Well, it does have bacteria. Coliform and heterotrophic are somewhat common. But usually not in high enough quantities or the harmful type.
The water in water supply pipes is almost always on the move. So it is diluting, and discouraging growth, these bacterial colonies. If water in pipes stagnates for long enough, bacterial colonies and viruses will grow more.
Ever seen a sprinkler pipe burst? It’s pretty nasty and smelly.
The water that enters the pipes from the water treatment plants doesn’t have any bacteria in it. It’s cleaned very rigourously, and a (small, extremely safe) amount of antibacterial chemicals are put into the water to make it doubly sure.
Once it’s in the pipes, there’s no way for bacteria to get in there. Pipes are solid. Plus, pressurised running pure water with antibac in it is a difficult environment for bacteria to successfully colonise. Even if a small amount of bacteria gets in there, it likely won’t find much to eat and will likely die soon.
In addition to all the above comments. Often pipework has biofilms that can be harmful. In the building that I work in, the water continously circulates to prevent biofilms and hot water systems are monitored to ensure that they are hot enough to reduce growth. Hot water cylinders are pasteurised on a regular basis.
Because of the presence of legionella bacteria we also dose the water with Chlorine dioxide at around 0.3ppm but this is not great because it degrades soft plastic seals and other fittings faster.
In large buildings keeping the water quality good to drink or more importantly shower in (legionella is respiratory) is an important function of the maintenance team.
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