A water tender, also known as a tanker in some regions, is a specialized firefighting apparatus designed for transporting water from a water source to a fire scene. Water tenders are capable of drafting water from a stream, lake or hydrant.

This class of apparatus does not necessarily have enough pumping capacity to power large hose lines (like a fire engine), though it utilizes a smaller pump to draft from bodies of water. Water tenders are used when there is no working fire hydrant within reach of other fire equipment, potentially supplying the fire engine(s) with a very rapid connection. Most water tenders are designed to carry loads of 1000 gallons (approx. 3800 litres) or more. In the US, 1000 gallons is the requirement in the NFPA standards. Some may carry up to or even upwards of 5000 gallons (approx. 19,000 litres) of water – even more with a trailer.