Choosing the best water for your house plants can be a bit of a daunting task – especially if you’re new to the hobby and had no idea that they were picky.
I water my plants with tap water, rainwater, and aquarium water, but all my plants can deal with tap water. It’s a deal we struck. My tap water is pretty good, so I’m not going to waste money on buying a water filter. Sure, they have the odd crispy tip, but they’re totally fine.
If you have bad tap water, but don’t want to spend a lot of fancy water, then you can buy something like Seachem Prime which will remove some of the nasties from your water.
It’s also important to pick plants that aren’t that picky. There are a couple of things to consider when selecting plants that are tolerant of crappy water:
- Does the plant need consistent watering and high humidity?
- Is the plant very common?
Plants that come from dry, arid, exposed areas in the wild don’t tend to be picky about water type. They’ll take what they can get. Plants that come from tropical rainforests are more selective, as they’re used to the finer things in life and plenty of them.
Climbing plants tend to be less picky than those that chill on the ground – in fact, plants that excel in low to medium light are usually the ones that will throw a hissy at the merest hint of chlorine in their water.
Extremely common plants like Monstera deliciosa and rubber plants tend to be less picky because they’ve been selectively bred over the years to deal with tap water, lower humidity, and general household conditions.
Tap water
Tap water varies a LOT, but if yours is ok, there is absolutely nothing wring with using tap water o your plants.
There are a lot of blanket statements out there such as ‘you can’t water Calathea with tap water’, and whilst that’s not entirely untrue, some Calathea, such as Peacock and Rattlesnake, often do totally fine with tapwater. Picky ones like White Fusion may develop brown leaf edges though.
You can always do a bit of trial and error. Try tap water, and if your plant takes issue with it, you can always switch to filtered. New leaves will grow, and you always chop the crappy ones off later.
Pros of tap water
- It’s so convenient. Right there in the tap
- You don’t need to store it
- Pretty cheap (depending on where you live)
- Contains minerals plants need
Cons of tap water
- It’s usually cold in the tap so needs to be left out to reach room temperature (not that I always do this)
- It can contain chloramine and fluoride (depending on where you live – you may need to ask your water authority to be sure) which plants aren’t massive fans of
Filtered Water
I don’t have a water filter, but they’re a fairly efficient way to get chloramine-free water. Filtered water is basically tap water with the chlorine removed, so you can get the samw result by adding dechlorinator (don’t drink dechlorinated water).
Pros of filtered water
- Filters out nasties
- Fairly cheap
- Doesn’t need to be refrigerated (but obvs can be) so you don’t need to wait for it to warm up before you can water
- Beneficial minerals aren’t filtered out
Cons of filtered water
- It can produce a lot of plastic waste
- A bit inefficient if you have a lot of plants, as the jug filters are pretty small
- More expensive than just dechlorinating the water.
Rainwater
Rainwater is often seen as the holy grail of water for house plants, but that’s not necessarily the case.
I do use it sometimes – I just put a big flexitub in my back garden and it fills up pretty quickly.
Pros of rainwater
- It’s free
- It doesn’t have any added chemicals
Cons of rainwater
- Can be a pain to collect/store if you don’t have a water butt
- Rain tends to be unevenly distributed – I have too much, but you may not get any at all
- We don’t actually know what’s in it – remember when acid rain was a big thing? It depends on where you live and if there have been any dust storms/volcanic activity/etc
Purified water
Purified water is water that has been filtered more than, er, filtered water.
Many people think that bottled water is purified, but it isn’t always. Here in the UK, a lot of tap water has lower levels of ‘bad’ chemicals like chloramine than bottled water.
Pros of purified water
- You can keep it at room temperature
- Low levels of impurities – it has to meet EPA standards even before it’s purified
Cons of purified water
- Expensive
- Not as widely sold as bottled water
- A lot the beneficial minerals are filtered out
- Plastic waste
Distilled water
Distilled water is water that has been, would you believe, distilled. We boil the water, collect the H2O in steam form, and condense it back into water, and anything that isn’t hydrogen or oxygen is left behind.
Pros of distilled water
- You can exactly control what’s going into your plants, so it can be good for hydroponics
Cons of distilled water
- Expensive
- Wasteful in terms of packaging
- You need to have a fertiliser with a complete macro and micronutrient profile, as your plants won’t be getting any additional minerals from the water
- It isn’t 100% effective – contaminants with a high vapor point, like Mercury, are difficult to remove using this system
RO water
RO (reverse osmosis) water is basically a fancy filter – it used to be an incredibly wasteful system, but has improved over the last few years.
Pros of RO water
- You can have a home system installed
- Has a remineralisation filter, so you don’t need to worry as much about micronutrients for your plants
Cons of RO water
- Expensive
- Not perfect – whilst distillation can leave behind heavy metals, RO systems aren’t great at removing fungi
Aquarium water
I’ve said this a tonne, but I’ll say it again – do NOT set up an aquarium just for the water. Unless you fancy doing a planted tank. Fish are a whole big thing when it comes to learning about their care.
Pros of aquarium water
- Room temperature or warmer, so it’s convenient to use
- Dechlorinated
- Has a bit of fertiliser from the fish poop, especially if you rinse the filter pads in it
- It’ll go to waste if you don’t use it
- Free (kind of, I mean, you’d be using it anyway)
Cons of aquarium water
- You need a freaking aquarium, or the inclination to carry it back from your local fish shop
- You need to work out if you want to collect it and store it (in which case you need a receptacle and space) or just grab a jug when you need it (which doesn’t work if you have a lot of plants
Can you water plants with well water?
It depends.
The good thing is that it often contains a lot of beneficial minerals like calcium and copper. On the other hand, it can also be harbouring bacteria.
I would recommend that if you want to use well water to water your plants, test it with a water test kit. Check that the pH is between 5.5 and 7, and check for high amounts of chlorine and heavy metals.
Can you water plants with sparkling water?
This is one of those things some people swear by. I simply won’t spend the money on my plants. They don’t deserve it.
There is anecdotal evidence that OCCASIONAL watering with sparkling water can help plants absorb minerals from it (I can only assume it gets into their system quicker due to the carbonation – like how I’m buzzed after half a glass of champagne).
There is also an argument that it’s easier for them to absorb carbon from carbonated water.
Sparkling water won’t solve all your plant’s issues, but a bit every now and again won’t harm them. If you want to give it a go, make sure it’s at room temperature before you water your plants with it.
Can you water plants with dehumidifier water?
Yes, and I do.
There are a couple of things to be cautious about though:
1 – Dehumidifiers are basically fancy fans, so the water deposited in the tank is COLD. Bring it up to room temperature before using it
2 – If I use mine near drying laundry, I smell it before using it on my plants, and if it smells of laundry detergent I don’t use it. It’s probably fine to use occasionally, but you don’t want detergent chemicals building up in the soil
Can you water plants with warm water?
I like to water my plants with warm water in winter. It can’t be hot – definitely more lukewarm – because hot water freezes quicker than cold water.
I don’t think there’s been much research done into using warm water on plants, but they definitely like cool water in summer (again, not cold), so why not?
Can you water plants with sea water?
No, it’s salty and can cause saline shock to the roots. There are SOME plants that can tolerate sea water, and you can use seaweed as a fertiliser, but watering your plants with seawater is just a quick way to kill them.
Can you water plants with tea?
USE COLD TEA
This is one of those things that no one’s really sure about. Don’t add milk, because that’s a great way to attract pests.
Basically tea SHOULD be high in beneficial nutrients, particularly nitrogen, but in studies, it’s not really had much of an impact, so the conclusion was drawn that plants can’t absorb it very well.
Again, there’s a lot of anecdotal evidence of people swearing by burying used teabags in their plants, soil, and their plants growing fifty times bigger overnight, and there’s also a lot of people saying it does nothing.
Also, tea is slightly acidic, which is isn’t that big a deal for most plants (unless you’re exclusively watering with tea) but some plants HATE acidic soil.
Guess which plant is being a diva about tea?
Yup, maidenhair ferns.
As if we needed another way to kill them.
Can you water plants with urine?
STOP IT
Except yeah, you can.
Watering with wee is NOT a good idea because water and urine are different (shocking, I know), however, you can add some urine to your water and it can add a bit of phosphorus and nitrogen into the soil.
Urine’s actually been used as fertiliser for years.
The more you know.
Note that I haven’t included a urine picture.
Can you water plants with softened water?
No, water softeners are usually comprised of salts that will damage your plants over time.
Every once in a while is probably ok, but don’t do it regularly.
Can you water plants with soapy water?
It really depends on how soapy.
There are a lot of different opinions on this because grey water (old bath or dishwater) has been (successfully) used to water plants for centuries.
I think it’s great to use in the garden, or even in the growing season when it won’t stick around for long, but I think used in house plants there’s a risk that any detergents build up in the soil over time.
Can you water plants with rice/pasta water?
Technically yes, and it might do them some good nutritionally (obvs cool it down first).
However, like all of those DIY fertiliser ‘hacks’ like burying banana skins and eggshells, you’re just opening yourself up to a massive gnat infestation. It is NOT worth it.
Final thoughts
My advice is that you should use tap water if you can. If it damages your plants or isn’t safe to drink then bottled is the way to go, but there’s no need to bother with distilled water.
A lot of people do swear by it, so I’m not saying it’s a bad thing you can’t do, but the lack of minerals in the water can lead to chlorosis and other nutritional deficiencies along the way.
