Generally, EPDM pond liners are considered safe for use with aquatic life and do not have a significant impact on water quality. EPDM is considered safer for water quality than other liner materials such as PVC which may contain plasticizers or other additives. Since EPDM is resistant to UV radiation, this means they do not break down easily. This greatly reduces the risk of contaminants leaching into the water over time.
That being said, it's still important to properly install and maintain your EPDM liner to ensure the best possible water quality in your ond. This may include taking steps to prevent algae growth such as providing adequate aeration and circulation, as well as regularly monitoring your water quality parameters such as pH and dissovled oxygen levels.
