Bigger is not automatically better. A full 100-gallon barrel on a slope exerts serious force on the base and spigot — size for your pad and your back.
30 gallon · balcony and tight side yards
Good for a single downspout on a small roof plane. Easier to reposition when empty.
50 gallon · most suburban beds
Sweet spot for weekly tree-bag refills without dominating the patio. Wheels help on turf.
100 gallon · multi-bed irrigation
Choose when you have level ground and plan to run multiple bags or soaker cycles per storm. Use the octagonal steel base on uneven yards.