The fact is that most of our taps run clean, safe, and perfectly drinkable water. So why bother with a water filter? It’s a good question!

The answer is that people filter their water for many purposes beyond the basic standards for water quality—so while you may not really need a water filter, there are plenty of good reasons for incorporating one into your household routines.

That said, it’s always worth thinking carefully before making any purchase, especially when some filters can run into the thousands of dollars. In today’s world of mindful living and conscious consumerism, it’s important to invest in products that you can truly get behind. So, here’s a decision tree to help you work out whether home water filtering is for you!

Question #1. Is your water safe to drink?

But first the basics: if you cannot trust in the safety of your water source, then you should be filtering at home. In the US, it’s estimated that 90% of people have regular access to safe drinking water, which leaves a worrying ten percent without this basic necessity—not to mention those who live in areas with unstable weather/ecosystems, which can suddenly affect water availability or quality.

If you’re unsure about exactly where your water comes from, or how well your local supplier treats your water, there’s a simple way to find out. The federal Environmental Protection Agency mandates that all suppliers produce and disseminate Consumer Confidence Reports, detailing all contaminants and their levels in your water.

Question #2. Does the idea of filtered water interest you?

Considering you’re reading this article, chances are that the answer to this question is Yes. The reality is that you can have access to standard quality drinking water and still be interested in home filtering. Just as some people prefer to buy organic when there are no specific health risks to GM or treated foods, many gain a boost in satisfaction and wellbeing from filtering pre-treated water to remove traces of chlorine, heavy metals, or dissolved sediments.

Question #3. Does your water taste bad?

water running from tap

There’s no surefire association between water quality and taste. The chemical and sediment odors might make some water sources offputting, while the minerals dissolved in spring water can make it extra appetizing. But there are also plenty of harmful contaminants that have no taste or smell, such as lead and giardia.

Likewise, safe drinking water—especially from public treatment works—doesn’t always taste the best. Traces of sediment as well as chlorine used to remove parasites can make their way into your glass. Filtering with a carbon cartridge, found in most models of home filter, will easily rid your water of these annoying impurities.

Question #4. Is your water too hard?

Most people living in hard water areas are aware of the minor annoyances that come with high-mineral content water. Your coffee maker and kettle can accumulate scale; dishwashers and washing machines are at higher risk of sediment build-up; soap barely suds, and water can taste overly tangy.

In more extreme cases, water hardness can affect the lifespan of household and kitchen hardware. Here, it can be a worthwhile investment to install a point-of-entry (POE) water softener where your water piper enters your home.

Question #5. Are viruses and microorganisms a concern?

A minority of multi-stage carbon filters can handle the super-fine level of filtration needed to deal with viruses—but most cannot. Instead, those looking to treat potentially dangerous water normally turn to reverse osmosis and ultraviolet radiation systems. Reverse osmosis (RO) filters apply pressure to a water stream, pushing it through a series of semi-permeable membranes, while ultraviolet UV models purify rather than a filter, destroying/disrupting pathogens at a cellular level.

Over-filtering: a word of caution. Once you enter the realm of reverse osmosis and other industrial-grade mechanisms, water can be filtered for contaminants smaller than a fraction of a micron. While this is good news for removing potential health hazards such as viruses, not all contaminants pose a danger to health.

Pouring a bottle of expensive spring water through an RO filter, for example, would remove most of the beneficial salts and minerals dissolved into the liquid. So, depending on where your water comes from, it’s important to weigh up the pros and cons of high-level filtering.

Read next: Comparing the different types of water filter.