Can You Drink Rainwater From a Water Butt? What It's Actually Safe to Use

It's one of the first questions anyone asks once they start collecting rainwater: now that you've got a butt full of it, what can you actually do with it? The water looks clean enough, it fell straight out of the sky, so surely it's fine for anything? Not quite — but the good news is that the list of things it's genuinely good for is much longer than the short list of things it isn't.

The short answer

Don't drink it, and don't give it to pets as their main water source. Do use it for pretty much everything else in the garden: watering beds, pots, lawns and greenhouses, topping up ponds (once it's had a day or two to settle), washing the car, hosing down patios, and rinsing tools and outdoor furniture. For most households that covers the vast majority of what a water butt actually gets used for anyway.

Why untreated rainwater isn't safe to drink

The water itself starts out clean, but by the time it's run off a roof, down a downpipe and sat in a butt for a few weeks, it's picked up things you don't want to swallow: bird droppings, moss and lichen washed off the tiles, dust, and whatever's settled on the bottom of the butt itself. None of that bothers a rose bed, but it's exactly the sort of thing that can carry bacteria harmful to people, and a butt with no lid or a cracked seal only makes it worse. UK guidance is consistent on this: water butt rainwater is classed as non-potable, meaning it hasn't been treated or tested to drinking water standards, so it shouldn't be drunk, used to make ice, or used for cooking or brushing teeth, however clear it looks.

What it's perfectly fine for

• Watering plants, lawns and pots. This is what it's collected for in the first place, and most plants actually prefer rainwater to tap water — it doesn't contain the chlorine or the lime scale that hard mains water does, which ericaceous plants like azaleas, camellias and blueberries particularly appreciate.
• Greenhouses and raised beds. Same reasoning applies, and it's one less reason to run a hose from the kitchen tap across the garden.
• Washing the car, bike or outdoor furniture. Soap and a sponge do the real work here, so the water doesn't need to be anything special.
• Hosing down patios, decking and paths. Fine for general outdoor cleaning where nothing's going to be eaten afterwards.
• Topping up a pond. Rainwater is actually kinder to pond life than mains water, since it doesn't carry chlorine or chloramine. If you're filling a pond from scratch rather than just topping up, let the water stand for a day or two first so anything it's picked up from the roof has a chance to settle.

The grey areas

A few uses sit somewhere in between, and it's worth knowing where the sensible line is:

• Watering vegetables and fruit. Watering the soil around growing veg with water butt rainwater is widely considered fine, since the plant's roots take up the water rather than it sitting on anything you'll eat. Where it's worth being more careful is watering directly onto leaves, salad crops or anything eaten raw close to harvest — a watering can spout aimed at the base of the plant, rather than a sprinkler over the top, is the easy way round this.
• Pets and wildlife. A butt left open can become a drinking spot for birds or a curious dog, and while the occasional sip isn't the crisis it might sound like, it's not something to actively encourage. Keep the lid on and provide a proper water bowl instead.
• Paddling pools. Fine for filling if the water's going on the lawn afterwards rather than being splashed about and swallowed by small children — in which case, stick to the tap.

Keeping it safe to use for everything above

A lot of this comes down to basic water butt hygiene rather than the rainwater itself being the problem. A lid that fits properly keeps out leaves, insects and light (which is what drives algae growth), and an occasional clean stops sludge building up on the bottom — we've covered exactly how to do that in How to Clean a Water Butt. A butt that's used regularly, rather than left to sit untouched for months, also stays fresher simply because the water isn't given the chance to stagnate.

If you're collecting into more than one butt, it's worth knowing roughly how much your roof can actually send their way in the first place — we've worked through the sums in How Much Rainwater Does Your Roof Actually Collect?, which is handy if you're trying to work out whether one butt is enough or you need to link a few together.

Making it easier to use what you collect

One reason people end up leaving water sat in a butt for too long is that it's awkward to get at — round the back of the shed, behind the bins, or just too far from where it's actually needed. RAINPOD is built around solving exactly that: it diverts rainwater from your downpipe to wherever your butts are easiest to site, and it has its own taps built into the pod itself, so you can draw off water right there rather than carrying watering cans back and forth. Using the water regularly, rather than letting it sit, is one of the simplest ways to keep it fresh — and having a tap close to where you actually need it is what makes that realistic day to day.

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The short version

Water butt rainwater isn't drinking water, and it's not meant to be — but for almost everything you'd actually use a hose or watering can for in the garden, it's not just safe, it's often better than tap water. Keep the lid on, give it an occasional clean, and use it regularly, and there's very little reason to let a drop go to waste.