I wonder if anyone has an opinion about the following...

I need to choose between four methods of watering my garden vegetables
rainfall becomes infrequent:

1) Use mains water via a garden hose (easiest option),

2) Use saved rainwater via a watering can

3) Maintain a large tub of mains water into which shredded seaweed has been
added (and perhaps a few comfrey leaves. I would water my plants with this
using a watering can.

4) As (3), except use rainwater instead of mains water.

Which is best. I expect that some will say (2), (3), or (4).. But is the
benefit (in therms of vegetable production) worth the extra time and
effort? (And, in my case, the cost of buying a watering can and extra butt
to brew the liquid fertlizer in...)

Jim