you could do that but it's not the best way...if you can, set up a wick system running a cotton rope or strip of cloth (i use towel strips) and run from a water source into the soil, as far as you can. wicks work best when 1st setting up your pots but can be added later if necessary...it's just easier to to do as soil is added. anyway, the cloth/rope strips will transport the water into the pot by itself (if you've ever left a wash cloth hanging over the edge of a filled sink you'll know what i mean) so the bigger the water tank, the longer you can be gone. i use the toilet reserve tank so water remains at a constant level but have seen swamp cooler plumbing used for this.

if you have time, you can also get a battery operated pump from gardenersupply dot com that works very well and has 10 stations it will feed for the life of the batteries, or about 4 weeks and it too can be set up on the back of a toilet to keep water level constant.