If you are drinking, copper or a variety of plastics from your hardware store; copper coils are available from stock, as are various plastics. The length of tube will depend on rate of heat transference; look for some components for humidifiers, air conditioning or freezer units.

Pressure will be important, as will the coefficient of expansion if you are talking about a range of temperatures, as some materials will fracture or split.

Water is not the best coolant to use.

Aluminum should also work well and likely be less expensive but if it is for potable water, it may impart an undesirable metallic flavor to the water.

TT3

Aluminum is toxic, be careful what you are using the water for.