You can use many things to haul water, just use a backpack and find the biggest water jug that can fit in it.
You can use water bags, if the water isn't so far away. You can use a bunch of 2L water bottles. If you're talking just a few plants, you're talking a just a few gallons.. You can also stockpile.. Get as many 2L bottles as you can, dig a hole make trips till all your bottles are full and cover them up. This way when your plants get bigger and thirstier, you'll have a bunch of water on hand and a bunch of bottles to keep filling and stocking.. If you plan it right, you can have a weeks worth of water in bottles already there.. Then once a week you fill them all back up..
Other than digging a trench and running a hose from an elevated stream, you're going to have to carry it