Should I install an inline water heater for my bathroom?
If you lag the hot water pipes you can help reduce the time it takes for the water to heat up as the water in the pipes will stay warmer for longer. Obviously this won't help first thing in the morning when the water's cold.

Installing a heater is certainly an option as it will reduce the 3-4 minute "lead time" - especially if you site it as near to the shower as possible. However you have to consider the following:


Is the cost of installing and running the heater less than the cost of heating the water that remains in the pipes and left to go cold.
If you pay for the amount of water you use then will the reduction in your water bill pay for the heater?
Can your shower be connected to an instant hot water feed? If you have a pumped shower then you probably can't do this.