Sungai Pencala is in a very unique position as it still has perfectly clean water at its source in Bukit Kiara. The water is drinkable there and is classified as Class 1. The river also supports a wide range of biodiversity in and around its water. However, less than 1km downstream, the river faces pollution problems from rubbish and sewage discharged by nearby residents. More recently, construction has begun nearby, and this is believed to be the cause of some very severe pollution problems in the river now (e.g. oil, waste metals, wires and rubber, etc.).

 

As the river progresses downstream, its water quality steadily deteriorates from a Class 1 to a Class 5 where it ends and joins Sungai Klang. This is because it flows through heavily industrialized areas of PJ as well as residential and commercial areas which are currently discharging waste liquids directly into the river or through drains.

 

Furthermore, over 70% of its original river course has been channelized, which is a cause for concern for biodiversity.  

The main sources of pollution include: solid waste thrown by the public into drains, restaurants washing their utensils next to drains, wet markets, and industrial discharge.