Drain Cleaner
Combine the following and then slowly pour down the drain you wish to clean:
1/2 cup salt
1/8 cup cream of tartar
1/2 cup baking soda
Follow with:
6 cups boiling water
Leave Overnight. In the morning, Flush with warm water for several minutes.
this is a good recipe, but i would caution that the 6 cups boiling water is not a good idea if the drain pipes are plastic, as you could melt them or cause a sag or leak.
To avoid using chemicals, pour 2-4 quarts of hot water down the drain weekly to keep it open. Do not use boiling water if you have plastic drain pipes, as they may melt or warp.
My favorite is to pour 1 cup warm vinegar into drain and cover. Vinegar is a mild acid, and can be left in the drain indefinitely without damaging drain pipes, so leave it as long as you like before using the drain.
If you like the smell of vinegar, the odor will also freshen the smell of the drain.
for further clarification, if you have pvc pipes (as opposed to plastic, typically found in mass-manufactured homes)- you can use boiling water without issue.