SJP,

This is a real puzzle because of the number of unknowns. Why do you carry empty milk jugs to water your plants. The jugs could be quart size or gallon size. The plants seem to be awful thirsty for watering two or three times a day. Not knowing the number of plants, their size and the bed size adds a special dimension to the problem.
I am going to take a stab at this anyway. If someone else has a better solution please chime in.
Lets see; 3 times a day at 2 one-quart jugs is 1 1/2 gallons per day for 5 days comes to 8 gallons while you are away. That is a lot of filling 2 liter bottles for your soon to be ex-roommate during this vacation. Hang 2 each 5-gallon buckets with hose attachments connecting each bucket and the last bucket has a pipe connection for a hose-bib battery operated controller which then has a manifold drip system to each plant. Problem solved cheaply but labor intensive.
Does your roommate share your water bill? Go with burdening your roommate with responsibility and take her out to dinner when you get back. Aloha