Trellis with plants growing up should work - remember that the oil delivery man will need access so don't create something he can't get round/through. We screened ours with shrubs but left a pathway.

In my previous house I regretted doing this as we could not get to the tank for painting it, so unless yours is maintenance free leave enough room! But it does work very well. Willow/Rush/Bamboo or Cane Screening bought on a roll can look good to with pots of colour in front.

I agree with Drc726. A tank that is poorly screened by plants looks worse than a willow hurdle etc. Also, if your plants lose their leaves in winter it looks bad too.

Ours is a dark green double bunded plastic, or what have you, tank. quite low to the ground. It is visible in winter through the shrubs/trees but for the rest of the year it isn't noticeable

I dont have one now but it had to be high up and green metal - but I found I didnt mind so much in winter but in the warmer months it was nice like yours MG if it disappeared. I cannot remember the other plants but one was Winter Jasmine - green in summer then the yellow flowers later.