Clear and pure, water is the elixir of life for all plants in ornamental and kitchen gardens. Chlorinated pool water also has the status of harmless purity. This cleanliness is of course thanks to chemical disinfection. When changing the water in the swimming pool or backwashing the filter, the question arises in the home garden as to whether chlorine water can really damage the plants. This guide explains in detail the conditions under which pool water can be used to water perennials, trees and lawns.
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Chlorine content determines plant compatibility
Water treated with chlorine is considered dirty water in Germany and may only be disposed of via the sewer. The reason for the regulation is the harmful effect of concentrated active chlorine on animals, plants and soil organisms. Since chlorine is often found in the form of organochlorine compounds in plants and animals, the substance is harmless in low concentrations. From a limit value of 0.3 mg/l, chlorine water is therefore rated as minimally contaminated and is no longer subject to the statutory waste water regulations. At the same time, this limit value marks the transition from water that is harmful to plants to water that is compatible with plants.
Waiting period is 48 hours
No special precautions are required to reduce the chlorine level in pool water below the limit value. Within 48 hours, the disinfectant breaks down by itself to such an extent that you can use the water for watering. If you want to be on the safe side, you can extend the transition phase by one or two days. To ensure that the family does not have to miss out on swimming fun during this time, simply fill the pool water into a cistern.
Water plants properly with pool water
Important premises must be observed for the competent use of chlorine water for plant irrigation. The rule of thumb for the swimming pool is: never drain all the water at once, as this will protect the foundation from frost damage. Furthermore, a water supply in the pool acts as a counter-pressure to the groundwater pressure and thus buffers the stress on the pool walls. Last but not least, there is an increased risk of waterlogging when pool water runs into the beds in a large torrent. In the worst case, the neighbor’s garden will also be flooded, so trouble is inevitable. How to do it right:
- Apply pool water using the irrigation method
- Use a submersible pump to slowly seep into lawns and large flower beds
- Water small areas, flower boxes or tubs with watering cans
Please note the soil conditions when applying stagnant chlorine water. On slopes or on heavy, compacted soil near the property line, the irrigation must be particularly slow so that the water does not run onto the street, onto the neighboring property or even into your own basement.
Chlorine-tolerant plants
Not all crops tolerate chlorinated water undamaged. While some ornamental and crop plants benefit from watering with pool water, other plant species are extremely sensitive to it. The following list summarizes which plants you can safely water this way and which species you should continue to provide with clear water:
Chlorine-tolerant plants:
- Mangold
- sugar beets
- rhubarb
- Beetroot
- asparagus
- Raps
- Most
- daffodils
- Rosen
- Tulips
Plants that are conditionally suitable for chlorinated water:
- potatoes
- tomatoes
- Spinach
- Kohlrabi
- sunflowers
- cucumbers
- peas
- leek
Chlorine sensitive plants:
- berry bushes
- pome and stone fruit
- French and pole beans
- cucumbers
- melons
- Salat
- The conifer
- all annual flowers
- seedlings and seedlings
Under glass cultures are basically not suitable for a supply of pool water. Indoor plants, greenhouse plants and plants in the conservatory react negatively to chlorinated water even if the limit value is below 0.3 mg/l.
