Water - water is not ever-lasting. Once we consume all the water, there wont be water, and that means there wont be life. Also, if we sum up the wasted water plus the contaminated water, we get a scary amount of water that isn´t being used properly or at all.
Land - land is also a basic need in our lives. We all now that there are alternative solutions to planting on land such as hydroponics, but they don´t work the same. In order to have plants (food), we need to have good and well-took-care-of land.
Air - we need air to breathe, preferably quality air. If we pollute the air we have, we´re damaging a very important resource, plus, if we cut too many trees like we do now, we´re only making things worse.
Hope it helped,
BiologiaMagister