I have two 5-gallon water containers and if I wanted to add a drop or two of bleach would that be OK?  Too much?  I know bleach is pretty potent.  This is not for really long term storage, just for maybe when power goes down for a few days.

Most tap water needs nothing else.
People say a table spoon of bleach is good for a 55gal drum, so maybe 10 drops would be good for 5gal.

Gallons of water to disinfect
(equivalent shown in brackets)
Amount of Household bleach (5%)
to add *
1 gal. (4.5 litres)    2 drops (0.18 mL)
2 1/5 gal. (10 litres)    5 drops (0.4 mL)
5 gal. (23 litres)    11 drops (0.9 mL)
10 gal. (45 litres)    22 drops (1.8 mL)
22 gal. (100 litres)    3/4 teaspoon (4 mL)
45 gal. (205 litres)    1 1/2 teaspoons (8 mL)
50 gal. (230 litres)    1 3/4 teaspoons (9 mL)
100 gal. (450 litres)    3 1/2 teaspoons (18 mL)
220 gal. (1000 litres)    8 teaspoons (40 mL)
500 gal. (2200 litres)    6 tablespoons (90 mL)
1000 gal. (4550 litres)    6 1/2 ounces or 12 tablespoons (180 mL)

From one of the PDFs in my collection......direct link to the document on the net seems to be broken now

heres another link to the same info

http://www.survivalmonkey.com/threads/shelf-life-and-food-storage-information.4123/

I have more commonly seen 8 drops per gallon. Also, 1 U.S. gallon = ~3.8 L and that table uses units of Imperial gallons, which most Americans will be unfamiliar with. Neither makes very much difference:

0.18mL/4.5k mL x 60 ppt =  ~2.4 ppm
0.72mL/3.8k mL x 60 ppt = ~11 ppm

This is still on the order of about 10 times the normal amount of chlorine found in chlorinated drinking water (0.1-1 ppm). As others have already said, if you're storing clean tap water in clean containers no additional chlorine is necessary.

Good catch. I was looking for a table I could copy and paste quickly and didn't catch the Imperial gallon distinction.

From FEMA website (fema.gov):


If you have questions about the quality of the water, purify
it before drinking. You can heat water to a rolling boil for 1
minute or use commercial purification tablets to purify the
water. You can also use household liquid chlorine bleach if
it is pure, unscented, 5 to 6 percent sodium hypochlorite.
To purify water, use the following table as a guide:

Ratios for Purifying Water with Bleach

Water                 Quantity Bleach Added

1 Quart                      4 Drops
1 Gallon                   16 Drops
5 Gallons                   1 Teaspoon


After adding bleach, shake or stir the water container and
let it stand 30 minutes before drinking.  

As stated, when storing known uncontaminated tap water you shouldn't really need to add this much, but it won't have any negative effect on you or the water. If the water smells like bleach when you need it (not a bad thing), just pour back and forth between containers a few times to aerate and let sit for a bit.

I got a free dropper at the pharmacy and it works out to 3mL for my 5 gal. MWC's.

I thought it was 8 drops per gallon....