The correct answer is option 4: It increases run-off losses.

Rainwater harvesting is a method of collecting and storing rainwater for future use. It is an effective device for water conservation, as it allows us to capture and utilize rainwater instead of relying solely on groundwater or other sources.

Option 2 is true because rainwater harvesting can help raise the water table by allowing rainwater to percolate into the ground and recharge underground aquifers.

Option 3 is true because with the increasing demand for water, rainwater harvesting can supplement the available water supply and help meet the rising water demand.

However, option 4 is false because rainwater harvesting does not increase run-off losses. Instead, it reduces run-off by capturing rainwater and preventing it from flowing away, thus reducing the chances of water wastage and soil erosion.