I made a self-watering bucket using two 10 litre buckets. The basic idea is quite well described on the web, but it seems to require some modifications to work with what I could find. In the examples above, the inner bucket seems to be supported at a good height by the outer-bucket, hence no supports are installed. This does not seem to hold for the buckets I got hold of. My bucket design is quite ad-hock, and probably a bit over-engineered, but I hope this will:

  1. Show that even a klutz with limited tools and abilities can build one.
  2. Add a bit of South-African flavour to the materials and shops.


  1. 2x 10l plastic buckets that fit in each other
  2. 4x plastic cups/mugs (Solid ones, not the thin disposable type. They need to bear some weight.)
  3. A length of plastic pipe to use as a filler pipe (2-4cm diameter, about 30cm or longer, depending on how high you want it to stick out.)
  4. A bunch of cable ties, 3-4mm width
  5. Potting mix (more about this below)

I did most of my shopping at Plastics for Africa, and got a piece of PVC hot-water pipe from Benbel’s. Some sites claim that PVC pipe could potentially leach dangerous chemicals into the water, others seem blissfully unconcerned. You may of course use some other kind of pipe, I just don’t know for sure how to know if it is “safe”. In any case, the total cost for all the parts was less than R60.


You don’t need anything special. The only “real” tool I used was a cordless drill. You probably need:

  1. Drill of some kind. Power drill preferably. Or anything that can poke 4-5mm holes in plastic I guess.
  2. A sharp knife, or scissors.
  3. A permanent marker (i.e. Magic Marker/Sharpie in USA)
  4. Optional: A circle saw with a diameter about 5-15mm smaller than your plastic cups. I just used a knife.


  1. Assemble the goods.
    Assemble the goods

    The components you need for a self-watering bucket

  2. Mark the cup positions by tracing around the cups using the marker.
    Marking the cup positions
    I used four cups, two as wicking baskets, and two just for support. This is probably over engineering, since 10l of potting mix should not be that heavy.
  3. Mark and cut out the holes for the wicking baskets.
    Cutting a hole for a wicking basket
    Accuracy is not very important here, so long as the hole is 5-15mm smaller than the cup. I ended up using a paring knife and cutting straight segments, approximating the hole as a polygon.
    The pretty and accurate hole.
    Ignore the four drilled holes around the cutout, I did this too early. I’ll tell you when to do them below. If you have one, the use of a circle-saw is indicated here… I used two wicking baskets, so make a similar hole on the opposite side.
  4. Drill four (or perhaps two would be enough?) holes along the top of each cup. I found it easier to drill with one cup inside. I put one of the wicking-basket cups inside, since it has to be full of holes anyway. These holes will be used to attach the cups to the bucket using cable ties.
  5. Since we are unique individual humans, it figures that the four cups will have unique individual holes. So, you have to number each cup, write its number on the bucket, and then make marks on the bucket corresponding to the holes in the cup. Also index one of the holes by making a longer mark on the cup and the bucket.
  6. Drill mounting holes in the bucket corresponding to the marks made above. I somehow forgot to take a picture of this and the next step, but you should be able to figure it out :)
  7. Drill a whole bunch of holes in the remaining part of the bottom of the bucket. These holes are for aeration. Mind not to drill to close to the mounting holes or the cutouts, or you might weaken those points too much. I used a 5mm drill bit, but that’s not too important. The holes must be small enough to prevent soil from falling through, but large enough to not get blocked easily.
  8. Cut a hole just larger than the PCV watering pipe in the bottom of the top bucket. The watering pipe will go through this hole into the reservoir.
  9. Drill a whole bunch of holes in the two cups that will be the wicking baskets, i.e. those that will be under the large holes made in step 3.
  10. Attach the cups to the bottom of the top bucket using cable ties.
  11. Trim off the excess cable ties
  12. Mark height of the drainage hole on bottom bucket and drill. The drainage hole should be about 2cm lower than the top bucket will be when it is resting on the cups. I used an 8mm drill bit for this hole. Here we see the completed buckets:
    Completed buckets
    Completed top bucket from above
  13. Cut a groove in the bottom of the PVC watering pipe. This is so that it doesn’t accidentally seal against the bottom of the bucket. I also drilled some small holes near the bottom of the pipe; not sure it’s really necessary.
  14. Put the top bucket in the bottom bucket and insert the watering pipe through the hole in the base.
  15. Fill the bucket with your soil mix. Start with the wicking baskets, wetting the soil and pushing it down quite firmly. Then contineu in 10cm layers. Between each layer water the soil well.
  16. After waiting a bit for the excess water to drain, fill the reservoir up to the drainage hole through the watering pipe.

A note about the soil mix

I did quite a bit of reading up about various soil mix options for SWCs, but a lot of it comes down to the qualities of the potting soil you start off with. Initally I tried clean Master Organics potting soil, but that did not seem to wick at all. Then I tried Culterra potting soil and that wicked quite well, but the soil did seem a bit wet. Finally I mixed 4 parts Culterra soil with one part perlite. This seems to work quite well. Perlite can be a bit expensive to obtain, but around Cape Town the best place I found to buy it is the gro shop in Observatory lower main road.

I bought the Culterra soil at the Stellenbosch Builders Warehouse Express. Unfortunately their stocking was quite sporadic. More recently I found out (I confirmed this with Culterra) the Builders Warehouse house brand (Lush) soil is in fact Culterra inside and works well too.