Mandaluyong is underlain with water tables which are still good sources of underground water for domestic uses. Water pumps and deep wells are still being used in many parts of the city to augment water supply from the Manila Water Company.

Surface waters such as the famous Pasig River and its tributary – the San Juan River – as well as six creeks traversing inland, serve as natural drainage flowing along the city’s southern and western perimeters.

And in the case of the Pasig, the river also serves as part of Metro Manila’s water transportation network.