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Why Does Rainwater Still Need To Be Filtered?

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Can you drink unfiltered rainwater straight from the tank? Rainwater has a strong reputation for being some of the freshest, cleanest water you can get. Logically, this makes sense; it comes straight from the sky without any added treatment chemicals or long journeys through rusty pipes, so there shouldn’t be anything to filter out… right?

While Australia doesn’t get enough rainfall for everyone to abandon their municipal water supplies, water tanks are a great way to reduce reliance on mains water or supplement bore water in rural areas. For homes close to water treatment plants or with particularly hard groundwater, rainwater can also provide an alternative source that doesn’t have a strong chlorine odour or muddy flavour.

However, although you can be fairly certain that your rainwater tank will be free from chemicals like chlorine and fluoride, water doesn’t become inherently safe just because it fell from the sky. Like any other water source, rainwater must be treated and filtered to make sure it’s safe for human consumption. In this blog, we’ll look at four major reasons why you should have a filter on your rainwater tank – and, of course, why a Complete Home Filtration system is the best option for that filter!

Quality Assurance


We often talk about how the Australian Drinking Water Guidelines have fairly generous margins and leave room for improvement in the quality of your water, but there can be no denying that some level of treatment and testing is vital for guaranteeing a reliable supply of safe water. Rainwater may not need the same kind of attention as water from underground aquifers or saltwater entering a desalination plant, but that doesn’t mean you can just drink it straight from the tank.

Even if the water is completely pure when it falls from the sky (more on that later), there are multiple contamination points that can add various nasties to your supply. Most of the water in your tank will have travelled along your roof and through your gutters, potentially picking up everything from dirt and dust to dead bugs and bird poo. A strong filter is required to make sure you’re not licking the inside of your gutters every time you want a glass of water.

Microbial Risks


One of the biggest benefits of using a rainwater tank is having a backup supply of water for a rainy day (pun only slightly intended). However, as any good survival guide will tell you, drinking water that’s been sitting still for too long is a very bad idea. The lack of chlorine in tank water may improve the taste, but it can also turn the stagnant water sitting in your tank into a breeding ground for microorganisms.

Chlorine and other disinfection methods are a vital part of the water treatment process, neutralising bacteria and protecting Australians from waterborne diseases. Allowing algae, protozoa, parasites, or bacteria to proliferate in your water tank can expose you to serious health risks. It is critical to make sure your water tank is either treated with chemicals like chlorine or has a dedicated ultraviolet disinfection system.

Chemical Contaminants


Rainwater tanks may be beyond the reach of ordinary treatment chemicals like chlorine and fluoride, but that doesn’t mean they are completely free from chemical contamination. Pesticides, heavy metals, and industrial pollutants can all exist as particulates – microscopic particles of solid or liquid matter that float through the air – and be caught up in rainfall.

Heavy metals can also be a significant concern for rural homes in mining regions, as metallic dust from the mines can be carried by the wind and settle on rooftops until rain comes along to wash it into the gutters – and straight into household water tanks.

Many of these chemicals (especially pesticides) can be toxic or act as endocrine disruptors, posing a particular threat to young children and pregnant mothers. A high-quality, low-micron water filter is a great way to protect your water – and your family – from potential environmental contaminants.

Sediment Removal


Even without bacterial or chemical contamination, rainwater tanks can quickly accumulate large amounts of dirt and dust. These sediments give the water a cloudy appearance and often lead to an unpleasant gritty texture and bitter taste/odour.

Elevated sediment levels can also cause frustrating, expensive damage to your home. Hard water damage is usually associated with limescale building up in pipes and appliances, but even though rainwater naturally has very few minerals to cause scale with, having coarse dirt or sand in the water can cause similar problems – often much faster. Sediments can erode your pipes, clog and damage water-using appliances, and leave dark mineral stains around taps and fixtures.

Another consequence of low mineral levels is that rainwater is often quite acidic, leading to increased discolouration as it passes through copper pipes. We often recommend our customers with rainwater tanks also look at a reverse osmosis filter and remineraliser, providing the combined benefit of an even higher level of filtration and a built-in alkaliser to counteract the acidity.

A large sediment filter is one of the most important parts of any rainwater tank setup, as it keeps accumulated dirt and dust from spoiling your experience and causing more harm than good.

Whole-Home Rainwater Solutions

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The best way to maximise the benefits of your rainwater tank is to have a filtration system that improves water quality, neutralises bacteria, stops chemical contaminants, and removes sediments before they get into your home. That’s where we come in!

Complete Home Filtration offers a premium whole-home rainwater filter with a 20-micron sediment filter, a 5-micron silver nano block, and a dedicated ultraviolet disinfection/treatment bulb. Just like our standard CHF-6000 systems, the rainwater filter has a high-flow design to provide great water throughout your home without sacrificing pressure (flow rate of 54-70 litres per minute).

To find out more about a rainwater filtration system tailored to your specific needs, send us a message below or fill out our enquiry form.