I'm fixing to start my vermicomposter. I'm using a damage 100gal Rubbermaid horse water tank. enter image description here

I'd like to know how many and of what sized hole to drill in the side for air. I figured maybe use a .25" bit to drill a hole every 6", all the way around and up and down the bin.

Secondly, would it be a good idea to get some pvc pipe and drill holes in it, adding two or three of these through the center of the bin, to get air into the middle of the bin, since it's so thick.

Lastly, I'd like to collect the worm water, for watering the garden. As you can see in the picture, it has a plug, but this might be too high and allow too much water to sit in the bottom. I was thinking of raising the bin up on logs, drilling 3-4 holes in the bottom inside the diameter of a 5 gal bucket, and sticking that underneath to catch the liquid. This might let a little water be on the bottom, but the excess should flow out and the rest should wick throughout the bin so I don't have to wet it as often. Does this sound like a good plan for the drain holes?

1 Answer 1


About the sides, .25" every 6 inches would indeed be adequate. I'd personally go with 1/2", but a 6" grid sounds great. The pvc idea could work, if they are cleaned regularly. I'd suggest using at least a 2" pipe for that, 4" being what I might personally use. That makes it far less likely to clog. Also, worms will go into the pipe through the holes, so if you were considering drilling straight through both pipe walls once, I'd suggest placing the pipe with the holes facing up and down, rather than sideways. That's because worms tend to go either up or down when trying to get back to their home environment, and you would trap less worms this way.

About collecting the water, your idea works but I would short sections of piping to the holes, to ensure drainage into the bucket, and not along the bottom of the tank as it will naturally do in the slow flow you will be getting. You could add valves or not. I'd also cap it with white is it's outdoors (the cap to prevent flooding/drowning worms and excess evaporation, white in color so that they don't cook in the sun). One of the biggest failures I see in larger vermicomposters are:

  • high temperatures - sometimes from materials heating in decomposition,. or from sun against the composter
  • lack of proper air flow, oxygen for the worms - Too much moisture can cause this, as can highly compacted conditions even in a properly vented system. You don't want the bedding to sour and poison the works either.
  • wrong level of moisture - to a degree the worms are adaptable, but in open topped systems, I often observe to wet and to dry conditions killing the worms. This can also occur in a capped system, but it's much easier to monitor and control there.

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