Rain water is often touted as a pure and natural alternative to tap water, but is it actually cleaner?

Rain water can be considered purer than tap water as it has no chemical contaminants.

However, it can still contain atmospheric pollutants, making drinking unsafe without proper filtration.

This article will review your drinking options so you can sip safely. So make sure you keep reading!

Tap Water vs. Rain Water: What’s the Difference?

Regulators treat tap water, but contaminants may still exist. Therefore, it’s best to research the quality of both sources and ensure appropriate filtration before consumption.

a half-filled water bottle sitting on a table in the rain

So, you’ve heard all the hype about rain water being cleaner than tap water. But is it really any better? Let’s take a look at the science behind it.

The table below highlights the key differences between rain water and tap water.

FeatureTap WaterRain Water
Water SourceTreated water from the local water treatment plant.Naturally collected from the atmosphere.
TreatmentIt is processed to remove impurities and is also disinfected.Not treated or processed.
ImpuritiesLow on impurities as it undergoes a treatment process.High (may contain pollutants from the atmosphere).
TasteIt may have a chemical or chlorine tasteFresh and features a uniquely clean taste.
SafetyGenerally safe for consumptionNot always safe due to pollutants
CostCheaper (provided by the government, infrastructure in place)Expensive (requires storage containers and filtration systems)

Drinking Water Pollution Sources

Water pollution is a pressing problem that affects the quality of the water we drink and use. Here are some water pollution sources.

  1. Agricultural farm runoff can contaminate water with pesticides, fertilizers, and other chemicals.
  2. Industries also contribute to water pollution by releasing harmful chemicals, heavy metals, and other pollutants into waterways. Sewage and wastewater treatment plants that are improperly maintained or operated can release pollutants into our water supply.
  3. Household pollutants such as cleaning products and personal care items that make up greywater can also end up in our water supply.
  4. Climate change and natural events like hurricanes and floods can overwhelm sewage and water treatment systems and cause runoff and erosion that washes pollutants into waterways.

How to Test the Purity of Rain and Tap Water

Gloved hand and ungloved hand holding a vial of rain water
To test water, collect a sample and use pH strips.

Testing the purity of rain and tap water is simple. To test rain water, use pH strips or a pH meter to measure the acidity or alkalinity and check if it falls within 5.6 to 6.0 on the pH scale.

Using a home water testing kit, you can check for contaminants like chlorine, lead, and bacteria. These kits are readily available and easy to use.

Regular testing is vital to ensure that rain and tap water remain pure and safe to drink.

If you find elevated levels of contaminants, consider using a water filtration system or seek professional advice.

Drinking Water Regulations

Primarily, as a general rule, you cannot drink greywater. But, as highlighted above, there are regulatory frameworks to control our general water use, especially regarding drinking water.

Regulatory Agencies

The Safe Drinking Water Act (SDWA) serves as the key federal regulation ensuring the purity of public drinking water. It mandates that all public water systems conform to EPA values.

The agency sets these standards to safeguard the public’s well-being by restricting the presence of pollutants in drinking water.

Contaminants regulated by the EPA include lead, bacteria, and pesticides, to name a few.

There are also standards for the number of certain minerals in drinking water, like iron and manganese.

These regulations apply to public water systems only. If you get your drinking water from a private well, it’s up to you to ensure it’s safe.

The EPA recommends that you have your well water tested regularly.

The Advantages and Disadvantages of Rain Water

A homemade harvest rainwater collector in use at an energy-efficient off-grid home
Rain water is sustainable and free!


  1. Rain water is a renewable, sustainable, and freely available resource.
  2. It’s also soft and gentle on your skin and clothing. Hence, you can use it for a range of household applications.
  3. Again, rain water is chemical-free and safe for drinking, although you must purify it first.


  1. Rain water is very costly regarding the initial investment in collection and storage equipment. Nonetheless, once everything is set up, you’re good to go, and there are limited maintenance costs.
  2. Pollutants can contaminate rain water in the air. Moreover, it can become contaminated if not properly stored.
  3. It may not be a reliable source in areas with low rainfall.

How to Safely Store and Use Rain Water

Storing Rain Water

To avoid contamination, ensure the storage tank you purchase uses food-grade materials, like plastic or fiberglass. Also, properly seal the tank to prevent contamination.

If the tank is outdoors, place it on a level surface to ensure stability and prevent leaks. Regularly clean the tank to prevent the growth of bacteria and other harmful substances.

Using Rain Water

Only use rain water for drinking or cooking with proper treatment.

Also, if you want to use it for watering plants or other non-potable purposes, ensure that you properly screen it to remove any debris, like leaves and sticks.

Seal or cover your tank to prevent debris from entering and keep out animals.

Also, avoid using rain water stored for a long time, as it may have become contaminated with bacteria and other harmful substances.

Other tips to increase the safety of your rainwater include:

  • Use proper collection systems: Invest in well-designed rainwater harvesting systems that include proper roofing materials, gutters, and downspouts to minimize contamination. Avoid using materials that may leach harmful substances into the collected water.
  • Regular maintenance: Regularly clean and maintain your rainwater harvesting system. Remove debris, leaves, and other contaminants from the roof and gutters to prevent them from entering the collection system. 
  • Invest in a first flush diverter: Install a first flush diverter in your rainwater harvesting system. This device diverts the initial runoff that may contain more contaminants away from the main collection tank.
  • Regular testing: Periodically test the quality of your rainwater to ensure it meets safety standards. Testing can include checks for pH levels, chemical contaminants, and microbial content.
  • Filtering mechanisms: Install effective filters in your rainwater collection system. They can include mesh screens, sand filters, and other filtration methods to remove particulate matter, debris, and impurities from the water.

Final Thoughts

Rain water is not necessarily cleaner than tap water.

While it may be free of chemicals added during treatment, it can still contain pollutants from the atmosphere and surrounding environment.

It’s essential to consider the source and potential contaminants before drinking rain water.

Ultimately, tap water is still the most reliable and safe option for drinking.

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