Reduce means to use a material/commodity in lesser quantity, e.g electricity and water. Reduce means a material that is used once is collected and sent back to a manufacturer so that they can make some other useful material from it. e.g., plastic cups and buckets, glass tumbler, paper, metal objects.
Reuse means using a thing over and over again instead of throwing it away. It does not involve the process of recycling either in small or large scale: e.g., used envelopes, plastic carry bags, bottles of jam.

(a) Unused water in the water bottle may be used for watering plant
(b) Close all the taps before you go to sleep.
(c) Avoid using a hose pipe for watering plants
(d) Wash vehicles only when they are dirty
(e) Use fan and light only when required
(f) Use solar water heating devices
(g) Use CFL in place of conventional bulbs/tubes.

The total amount of fresh water is more than enough to meet the needs of human  beings. But due to its uneven distribution, wide seasonal as well as yearly fluctuation in rainfalls and wastage water shortage is a chronic is a chronic problem in most parts of the world.

(a) recharging the ground water
(b) can be used for irrigation
(c) treated municipal water can be used for washing cars, watering the gardens
(d) certain pollutants in sewage water can be become fertiliser for various crops.

(a) Habitat, food, protection to wild life.
(b) Help in balancing CO₂ and O₂ of atmosphere.
(c) Improves water holding capacity of soil.
(d) Regulates water cycle
(e) For human being, they are the source for all essential commodities like, fuel wood, timber pulp and paper etc.
(f) It provides useful products like fruits, resins, gums, essential oils, bidi wrapper etc.