Drinking water is generally considered safe, at least when it comes to bacteria and viruses. But many people are rightly worried about the potential for ingesting toxins through their drinking water. Here, we look at some of the risks associated with drinking water and explore how filters can help reduce these.
Types of toxins in drinking water
Drinking water in the US is generally considered safe, thanks to strict rules imposed by the Environmental Protection Agency (EPA). However, these regulations are prescriptive and focus on a few specific sources of contamination.
PFAS
Just this year, the EPA enacted standards limiting the amount of certain PFAS compounds in drinking water. PFAS (per- and polyfluoroalkyl substances) are a widely used group of chemicals that have useful chemical properties. However, increasingly we are becoming aware of their negative effects on human health. The problem is, PFAS often persist for many years in the environment and so they lead to contamination. This PFAS contamination map from EWG highlights the scale of the problem. As a result, the EPA has imposed limits for some of these compounds:
Compound (Enforceable level in parts per trillion or ppt)
- PFOA (4.0 ppt)
- PFOS(4.0 ppt)
- PFHxS (10 ppt)
- PFNA (10 ppt)
- HFPO-DA aka GenX (10 ppt)
These standards should lead to improvements, however, they are just the tip of the iceberg given the scale of the PFAS problem.
Toxic metals
Another common source of drinking water contamination is toxic metals. We all know that lead pipes used in previous centuries resulted in widespread lead poisoning. Yet lead is still a problem all around the country, including metropolitan areas like Chicago as reported by NPR in April. But there are many other metals that still make their way into our drinking water. These include aluminum, copper, zinc, and cobalt.
Pesticides, fertilizers and other agricultural chemicals
Have you ever considered how your drinking water reaches the faucet in your house? In much of the US, the chances are that the water has been extracted from a river. This means it has likely been polluted by runoff from farms. This can include all sorts of chemicals including pesticides, herbicides, and fertilizers. Many of these chemicals have been linked to human health problems. Moreover, recent studies have linked some of these chemicals to PFAS, meaning you may be getting a double whammy.
How to avoid toxic chemicals in your water
If you’re worried about toxins in your water, you can do a few things. Firstly, you could choose to drink only bottled water. However, many plastic bottles contain PFAS or other chemicals. So, you may actually still face some risks. Some people might think of boiling all their water before drinking it. This works really well to clear biological contaminants, such as bacteria or parasites. However, it will typically not affect most chemical toxins. The better option is to filter your water.
There are many different types of water filter, from jugs that you fill and place in your fridge, to ones that are installed on your main water supply. These all use various filtration technologies. Below, we look at the most effective of these:
Mechanical filters
A mechanical filter is filled with material that will stop any particles above a certain size from passing through. Typically, they are sold according to the minimum size that will pass through. So, you might see a 50 micron filter, which will block anything bigger than that. These filters are best for removing physical contaminants from your water as well as parasites and some larger bacteria.
Reverse osmosis
Osmosis is the process where chemicals flow from an area of high concentration to one of low concentration. It is how oxygen flows from your lungs to your bloodstream. As the name suggests, reverse osmosis is the opposite process. This is where you use special membranes to allow chemicals to flow from areas of low concentration to high concentration. This reduces the amount of that chemical on one side of the membrane, resulting in filtered water.
Activated charcoal
Active charcoal, also known as activated carbon, is carbon that has been carefully processed to greatly increase the surface area. This is done by creating millions of tiny bubbles in the material during manufacturing. These tiny bubbles allow it to use a process called adsorption (yes, with a ‘d’) to capture many chemicals that flow past the filter. Activated charcoal is the typical form of filter used in countertop and refrigerator water filters. It is good for filtering agricultural chemicals, organic substances, and some other chemicals. However, it typically has no effect on the level of PFAS.
Ion exchange
Ion exchange is the process used in many water softeners. To understand how this works you need a reminder of your high school chemistry. An ion is a charged particle - a chemical particle that has either had 1 electron removed (a positive ion) or an electron added (negative ion). In ion exchange, water flows through a substance that is able to swap one set of ions with another. In a water softener, this typically means swapping calcium ions with sodium ions. So, ion exchange filters are able to reduce water hardness. But they are also effective at reducing radioactive material and lead as well as some other metals.
How to choose the right filter
Choosing the right filter for you depends on several factors. Firstly, do you know what toxins are in your water, and how high the concentrations are? There are companies like Tap Score that sell testing kits so you can check exactly. Or there are online sources like the Environmental Working Group that provide databases of known water quality issues. Once you know what you’re dealing with, you need to decide on what you can afford.
Permanent installation or not?
The next decision is whether you want your filter to be permanently installed. This could be installed where the water enters your house, or it might be installed in a specific location, such as in the kitchen. Alternatively, there are portable or countertop water filters that may provide enough performance for your needs.
Multi-stage water filters
Then, consider how much filtration you need. A single-stage filter will typically be great at one type of filtration, but won’t remove all potential contaminants. Often, a multi-stage filtration system will consist of a mechanical stage to remove large particles, an activated charcoal stage, and a reverse osmosis stage. This combination ensures the best performance. However, it will definitely cost you more.
Ongoing costs
Having chosen which type of filtration you need, the next step is to check on the ongoing costs. All water filters need to be replaced every few weeks or months. This is usually achieved by removing the used filter cartridge and replacing it with a new one. Depending on the filter, these replacement cartridges may be a few dollars or tens of dollars or more.
Monitoring the impact
Once you have chosen and installed the water filter, how do you know how effective it is? Well, the easiest way is to test yourself and your water to see what changes. For example, you could take a PFAS blood test like the one we have developed. This will show you how effectively you have reduced PFAS intake by installing your water filter. However, you should be aware that PFAS can also enter your body by many other routes.
