20 Interesting Facts About Tap Water

For most people, clean tap water is something taken for granted. You probably don’t even think about it. But it often gets an unnecessarily bad rep, especially when contamination incidents show up in the news. It turns out tap water is a surprisingly complex subject. Here are some facts about tap water.

1. Tap water usually goes through a 4-step treatment process before it goes to your pipes…

Water utilities usually draw their water from local rivers, lakes, and aquifers. The water goes to a treatment plant where it typically goes through a 4-step process to make it safe for people to use. First, chemicals are added that bind to dirt and dissolved substances. The clumps that form are called floc and the whole process is called coagulation and flocculation. Next, the floc sinks to the bottom, and the resulting water goes to the next step. Here, the water gets filtered through layers of sand, gravel, and charcoal to remove even more particles and dissolved substances. Lastly, the water is disinfected (typically using chlorine, chloramine, or ozone) and sent to a storage tank before it heads to your house.

2. …but some places may need more steps due to the conditions of the original source of the water.

The quality of the source water varies widely from place to place. For example, water in areas with lots of farming activity has higher levels of nitrate. Water in western US states typically has more salt in it. These places require additional steps in the treatment process to make the water usable.

3. The mineral content of tap water determines how “hard” or “soft” it is.

The hardness of the water is based on how much calcium and magnesium is in it. As water flows underground, it naturally picks up minerals from dissolving rocks. As you would expect, some places will have much harder waters than others. If the water is too hard for your liking, you can change it using a water softener.

4. Hard tap water isn’t harmful to you, but it can damage your plumbing.

Hard tap water doesn’t harm you at all. In fact, it might even be slightly beneficial if you drink the tap water (extra calcium and magnesium). But those same substances can really mess up your plumbing. High mineral content in the water causes the formation of a chalky buildup on the inside of the pipe (limescale), especially for pipes that carry hot water. If it gets too thick, the pipe becomes pretty much clogged and needs to be replaced.

5. Hard tap water also reduces the effectiveness of soap.

You can tell roughly how hard your tap water is by how much soap lathers when you wash your hands. The less it lathers, the harder you water is. Calcium reacts with soap (specifically the sodium stearate in soap) to form soap scum (calcium stearate). This reduces the amount soap molecules available to clean whatever you’re cleaning.

6. Tap water is tightly regulated…

The Environmental Protection Agency (EPA) regulates the safety of tap water in accordance with the standards in the Safe Drinking Water Act. There are currently more than 90 contaminants that the EPA monitors and has standards for. Your tap water has to meet those standards before it gets to you.

7. …but sometimes dangerous levels of contaminants can slip past the regulations.

This can happen with lax enforcement of the existing standards or a lack of oversight. The recent water crisis in Flint, Michigan was the result of improperly treated water causing lead from old pipes to leach into the water. The water source Flint switched to had much more chloride, which corrodes lead pipes, and the city didn’t add enough orthophosphate (which forms a protective film along the inside of the pipe that separates the water and lead) to compensate.

In other cases, it could be the result of local water systems simply not having the resources to upgrade existing infrastructure. This mostly happens in lower-income rural areas, particularly in Oklahoma and western Texas. The EPA doesn’t regulate private wells at all.

Lastly, it can also happen because there’s a huge number of pollutants and contaminants that can get into the water supply. Many of them don’t have standards because there isn’t enough evidence to come up with them or not enough resources to monitor them all. As a result, some states, such as California, have decided to go beyond what’s legally necessary in terms of monitoring contaminants.

8. Fluoride in tap water helps slow tooth decay.

Water utilities usually add fluoride to tap water where it’s necessary (fluoride can get into water through natural means) to help slow tooth decay. It helps your teeth remineralize by forming a thin layer (consisting of fluorapatite) over your teeth that’s more resistant to acid from bacteria than the original enamel (hydroxyapatite).

9. The quality of your tap water is partly dependent on your pipes.

The stuff your pipes are made of can leach into your water. Old lead pipes were discontinued and are being replaced for that reason. But newer pipes also have problems. For example, pipes made of copper leach small amounts of it into the water, which can stain faucets and other plumbing fixtures blue-green over time. If you’re concerned about it, you can just leave the water on for about a minute before using it and use the initial water to water some plants or something.

10. Boiling water can kill biological contaminants…

Bacteria can sometimes get into tap water either from improper treatment or from a break in the water line somewhere. Boiling the tap water will ensure that you kill any harmful bacteria.

11. …but it can also concentrate the non-biological ones.

Boiling water evaporates some of it. But many contaminants don’t evaporate along with the water, so you’ll be concentrating them in the remaining water. You can use a water filter to fix this problem.

12. Bottled water isn’t always better than tap water.

The EPA regulates tap water, but bottled water is regulated as food by the Food and Drug Administration (FDA). Although they use similar standards, sometimes the enforcement of those standards isn’t as strict for bottled water. That can lead to situations where sometimes bottled water has more contaminants than tap water. Plus, bottled water is much more expensive, and most people can’t tell tap water from bottled water anyway.

13. In fact, sometimes bottled water is (filtered) tap water.

Brands like Dasani and Aquafina are essentially filtered tap water. In fact, any bottled water that says something about being from “municipal”, “public”, or “local” sources means it’s tap water. And you have to pay extra for it? Lame.

14. Water towers are tall for a reason.

Ever wonder why water towers are often the tallest structure in the surrounding area? It’s because that’s how water pressure works. The mechanics of water pressure are such that any water pipes connected to the water tower can only deliver water up to the height of the water level inside the tower. If some part of a building was higher that that water level, that part wouldn’t have any running water.

15. The average American family uses more than 1135 liters (300 gallons) of water a day at home.

For indoor use, water for flushing toilets is the largest share. Next comes showering/bathing, then faucets, and then washing machines.

16. Contrary to popular belief, replacing regular toilets, showerheads, and washing machines with water-saving ones is more effective than simply using less water.

Since they account for much of the total usage, it makes sense that switching to water-saving versions would be very helpful for water conservation. Water-saving showerheads have a GPM (gallons per minute) rating, while toilets have a GPF (gallons per flush) rating.

17. Leaks account for about 11% of indoor household use.

And it’s a huge problem. It accounts for about 3.4 trillion liters (900 billion gallons) of water wasted throughout the US every year. Fix those leaks! It’ll save you money and help save the planet.

18. Outdoor use accounts for about 30% of total household water consumption.

This is mainly for landscape irrigation. But it’s often a lot higher for dry areas. It’s one of the reasons why some of these areas are offering financial incentives to switch to less water-intensive landscaping.

19. Global warming threatens the freshwater supply.

It does this from many different angles. Higher temperatures increase the demand for water and also evaporate more of the water in reservoirs. Also, rising sea levels can contaminate freshwater sources near the coast with salt. In addition, more severe droughts reduce the amount of precipitation available to refill reservoirs.

20. This is making some areas consider wastewater recycling and desalination.

With the effects of global warming increasing as well as the overall demand for water, some areas are looking to new techniques and technologies to make previously unusable water into water safe for the tap. These include desalination (usually by forcing water through very fine membranes) and wastewater recycling (using rigorous treatments to turn sewage and other wastewater into potable water).