Water for orchids

When it comes to watering orchids, there are a number of opinions about which type of water is best. For a beginner, this can be confusing and perhaps a little overwhelming. In this post, I’ll try to explain the main different types of water I have come across in my reading. Hopefully by the end of this post, you’ll have a better understanding.


A note on water before we start: temperature. When you are watering your orchids, it is a good idea to water with room temperature or tepid water. This reduces the likelihood of your orchid’s roots being shocked by anything too cold or too hot. I would not recommend using ice cubes to water your orchids.

Tap Water

Two things to consider with tap water. The first is the hardness of the water. Most orchids prefer water that is soft i.e. it has low levels of dissolved solids. It will depend on the area you live in whether you have soft, medium or hard water. A relative of mine had hard water where she used to live – her kettle would regular fuzz up with limescale and every year or two she’d have to buy a new one. The same things that fuzz up kettles and washing machines can eventually cause problems for your orchids.

Secondly, the pH of the water. Ideally, the pH of the water should be around 7 on a pH scale. If it goes much higher than 7.5 then the water starts to become to alkaline, which can prevent the absorption of nutrients, leading to deficiencies. Slightly acidic water (6.5) is less problematic, but you can purchase products to help balance the water’s pH.

Where tap water is concerned, you can have your water tested for hardness and pH at aquatic centres. Some garden centres have aquatic sections within them as they sell fish pond equipment. Alternatively, you can purchase water test kits and meters online or at pet stores. TDS (Total Dissolved Solids) meters and pH meters are available relatively cheaply and are reasonably reliable – not completely accurate, but they will give you a rough idea. Tap water also has additives that can affect orchid feeds, so when using tap water you can reduce the quantity of feed slightly to accommodate.

Equipment for testing water
From left to right: Water test kit purchased from an aquatics centre, a TDS (Total Dissolved Solids) meter and a pH meter.

If you have hard tap water with an alkaline pH, you could follow the advice above to change it, or seek another option.

Rain Water

Although I haven’t used rain water on my orchids, a number of other orchid growers do. Using rain water removes the issue of water hardness and pH imbalances. The UK normally receives an average rainfall above 500mm a year (some parts of the UK can receive 2,000mm of rain – according to the Met Office). So, we are in an ideal country to collect rain water to use on orchids!

Unlike tap water, rain water does not hold as many additives. When you add fertiliser, you may need to adjust the quantity slightly to reflect the lower number of additives.

Reverse Osmosis Water

Commonly referred to as RO water, presumably because saying Reverse Osmosis water several times in a sentence is hard going! Some orchid growers use RO water for the same reasons they may use rain water; it has next to no added chemicals.

There are a number of different RO systems available on the market, each producing different quantities. From what I understand, the RO system needs to be connected to your tap water system. The tap water is then stripped of chemicals, ions etc through a filtering process, and is collected into a tank at the end. RO water can take time to produce so it may not be suitable for larger orchid collections that require watering every day.

Distilled Water

Distilled water is similar to RO in that it has had impurities removed. However, the process of removing chemicals etc is achieved by boiling not filtering. The steam produced by boiling the water is then ‘distilled’ into containers. Distilled water can be purchased online or at certain stores.

I hope this was useful, and will give you a better understanding of the different types of water you can use on your orchids.

Happy growing!




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