This is a pet issue of mine.
I believe that Catholics shouldn't be a bad example by being wasteful (food, water, electricity, money) because we should be grateful for God's gifts. When you waste something, you're throwing it back in the giver's face with apathy. If you throw gifts back in the giver's face, how can you expect further gifts?
The "overpopulation" nutcases miss several important points.
For example, once you're heating and cooling a house, it doesn't cost extra to add more souls to the house. The family room light (Compact Fluorescent, of course!) will be on, and everyone can use it.
The trick is to not be a "consumer" or gadget-addict. If each kid needs his own PC and/or entertainment center, then YES, kids will cost you more electricity. But playing -- inside or outside -- costs no electricity.
Even laundry is no issue if you have a front-loading washer, you wash with cold water, and you line-dry your clothes.
I bet my family of 5 spends less money and electricity on "laundering clothes" than most DINKs (double-income-no-kids).
We also wear our clothes until they're dirty (or smelly, or "shower day", whichever comes first). We use bath towels 4 or 5 times before we wash them. Just hang them up and they dry out fine!
We also don't take daily showers unless we have a good reason. In the summer I take a shower after I've worked outside, which is hopefully every day. But in the winter it's easy to go 3 or 4 days without a shower. It's actually BETTER for you, especially your skin. In the winter your skin will be dry if you wash it too much.
And remember, after getting some sunlight, your body needs up to 2 days to absorb most of the Vitamin D that was produced. So if you take daily showers, you probably won't get enough Vitamin D.
Matthew