How to Grow
The Venus Flytrap

The Venus Flytrap Care Guide at


Venus Flytraps Must Have Pure Water

Most water will kill Venus Flytraps. As mentioned elsewhere at, Venus Flytraps need very pure water; tap water and well water is likely to damage or kill a Venus Flytrap. "Pure" water means water that has none or almost none of dissolved minerals or other soluble material in it.

Dirty rain water that has been collected and stored in an open barrel, with perhaps some dust or dirt settled at the bottom, some algae growing in it, some mosquitos breeding in it, with some dead insects, leaves and other waste material floating in it, may look bad and not be healthy for humans to drink, but it is in almost all cases actually purer than tap water or bottled drinking water, from a Venus Flytrap's point of view. The reason is that your tap water and bottled drinking water, while generally safe for you to drink, very probably contains a range of dissolved mineral salts that are harmful to Venus Flytraps, while the dirty and discolored rain water is likely to have far less mineral and other dissolved content and is much more suitable for Venus Flytraps.

Because tap water and other household water, or well water, or bottled drinking water, is likely to have too many minerals dissolved in it (too high a TDS, "total dissolved solids") to use for Venus Flytraps, there are three primary methods to obtain pure water—

How to get pure water:

Buying water

For a few up to several dozen Venus Flytraps or other carnivorous plants, buying water is fairly inexpensive, costing very little per gallon or liter. It's important to buy only water that has been produced by means of distillation, deionization or reverse osmosis, or a combination of these processes. It's important to read the label on any bottled water to make sure that the distilled, deionized or reverse-osmosis water has absolutely nothing added to it after processing and before bottling.

What type of bottled or other commercial water to buy?

Collecting water

Some people are fortunate enough to live in an area where there is unusually pure water from the tap or from surface deposits or streams, water from recent snow melt, for example. But the water most people have available from the tap, wells, rivers and ponds is not pure at all, and without testing with a TDS meter, should be avoided.

If it rains often enough in your region, you might be able to set up a simple system to capture and store rain water for your Venus Flytraps and other carnivorous plants. Rain can be captured into a barrel as it falls from a valley in a roof where two pitched sections meet at right angles, or water from a roof-gutter system can be diverted into storage containers.

rain water collection tanks
Storage tanks for rain water collected from a metal barn roof

Making Pure Water

There are two primary ways to make pure water yourself, or more accurately, to process the tap or well water you have to make it pure enough to use for Venus Flytraps: use a distiller or use a reverse osmosis system. NOTE: Simply boiling water makes the water worse; the pure water evaporates as steam and is lost; the water left behind in the pot contains an even greater amount of dissolved minerals than it did before it was boiled.

People who use water distillers, usually heated with electricity to convert water to steam, often consider them expensive to use in comparison with the relatively small amount of pure distilled water they produce. Reverse osmosis systems by contrast, while removing not quite 100% of the non-water material dissolved into the source water, are much more efficient, end up costing much less per gallon of water, and produce water almost as pure as rain or distilled water.

For making enough pure water to adequately supply a medium sized collection of dozens of plants (if you can't collect rainwater), a compact reverse osmosis system is recommended. There are numerous businesses and websites online that sell variously configured and customized reverse osmosis systems using standardized, inexpensive and interchangeable parts; an internet search for "reverse osmosis" will yield numerous results.

reverse osmosis system
Compact reverse osmosis (RO) system, less than 24 inches in height

Regardless of where the water for your Venus Flytraps comes from, it should be tested occasionally for TDS (total dissolved solids). Reverse osmosis membranes lose efficiency after some months and need to be replaced when the TDS count of the water exceeds 40-50ppm (parts per million). Please see about TDS.

Stephen Doonan,