How greywater affects plant growth

Reusing greywater for plants and trees is a great way to save money and use less water. However, it could have its drawbacks. In this blog post, we are going to review a scientific paper that looks into the effects of greywater on plant growth.

Reusing greywater for plants and trees is a great way to save money and use less water. However, it could have its drawbacks. In this blog post, we are going to review a scientific paper that looks into the effects of greywater on plant growth. Here is the link to the original paper https://www.researchgate.net/publication/236871967_Effects_of_greywater_irrigation_on_plant_growth_water_use_and_soil_properties

Reusing water helps to preserve eco-system. Also, reusing greywater for gardening and house choirs can reduce pressure on the water supplies. It will require a lot of effort and time, but it pays of in the long run and helps to cope with the water scarcity. However, there could be issues related to environmental pollution, because greywater may contain chemicals dangerous to the environment. In addition, this study focused on the chemical effect of greywater on the soil.

In this study silverbeet, was used as an example. The scientists measured how greywater affected plant growth, plant water use, soil pH, electrical conductivity, nitrogen and phosphorus. This blog post focuses on plant growth only. Please see the original article for more details. There were four water treatments involved:

  1. 100% potable water.
  2. 100% greywater.
  3. 50% greywater and 50% potable water mixture.
  4. Alternate with 100% potable water for one irrigation and 100% greywater for the next.

According to the statistics of the experiment, the dry biomass of silverbeet was not significantly affected by any of the water treatments. Although, there was a slight reduction in growth after irrigation with greywater. In my opinion, it is not a surprise, because greywater is more alkaline (pH 10.5) and contains more Nitrogen and Phosphorus. Whereas optimal pH for plant growth is 5.5-7.0. It is possible that silverbeet is tolerant to the toxic effect of greywater than other plants. This study has investigated silverbeet only.

In conclusion, there is nothing wrong with using greywater for irrigation. In my opinion, it would not cause any harm if used in moderation and if you know where the greywater comes from.