Collecting and Using Liquid Fertiliser (Leachate)

13 July 2020  |  HOTBIN Composting

Can I collect the liquid and use it as a fertiliser?

Yes - you can collect the liquid fertiliser (leachate) and pour onto your plants and soil.

You can expect up to a mug full (300ml) when draining regularly but please be aware that the amount drained from the HOTBIN will vary from user to user based on the types of waste added to the HOTBIN.

PLEASE READ our guidelines for collection & safe use of leachate

  • Do not use the liquid fertiliser (leachate) if there is a putrid smell or if you are draining it from an anaerobic HOTBIN.
  • Water the soil around plants, avoid wetting or spraying any foliage
  • Always dilute liquid fertiliser (leachate) at a ratio of 1:10 (1 part liquid fertiliser (leachate) to 10 parts water)
  • When using any compost, fertiliser and or leachate to feed your veggies, fruit or salad it is recommend that you don’t eat those items straight away, leave it a minimum of 20 days to allow microbial organisms in the soil to consume it.
  • Always thoroughly wash edible items that you feed with compost, fertiliser and or leachate, especially uncooked items.
  • Once collected ensure the liquid fertiliser (leachate) is used within a 2-week period
  • When draining we always recommend wearing gloves.

The liquid created by the HOTBIN does not have a high NKP (Nitogen, Potassium, Phosphorus) value so can be used as a fertiliser. The brown odourless liquid will be mainly Fulvic Acid and Humic Acid - both improve the uptake of minerals and can stimulate plant growth. Ensure you have collected an odourless, dark brown liquid. Take care if you have collected a fruity / acidic yellowish liquid, or a black pungent drain like thick slimy goo – see ‘why does the liquid fertiliser smell’ below.

How do I collect the liquid fertiliser (leachate)?

With the HOTBIN Mk 2 & HOTBIN Mini the liquid fertiliser (leachate) will collect in the bottom of the HOTBIN under the aeration base plate, this can then be drained off by unscrewing the cap at the bottom of the bin on the right-hand side. You can put a shallow container (a takeaway tub is ideal) under the tap and collect the liquid. You should drain the liquid regularly to avoid too much liquid collecting in the base and spilling out through the mesh plate.

Do not worry if you have a HOTBIN Mk 1 you can still collect the liquid fertiliser (leachate) it will just require more of a DIY solution. Using a shallow container put this if front of the mesh plate at the bottom of the HOTBIN in the middle. Set the tray on the ground and push tight to the mesh plate. Alternatively get a sponge on a tray and set this against the mesh plate (be careful not to fully block the mesh), this will absorb the drips.

You could also place the HOTBIN on a slab and raise this up using some bricks, this allows you to place the container slightly under the HOTBIN ensuring all the liquid is collected including drips.  

You can also let the leachate drain away to soil if this is where the HOTBIN is situated.

Use a small tray to collect leachate Leachate collected using a sponge








Should I dilute liquid fertiliser (leachate) produced by the HOTBIN, what dilution?

Yes. You should dilute the liquid fertiliser (leachate).

Always dilute liquid fertiliser (leachate) at a ratio of 1:10 (1 part liquid fertiliser (leachate) to 10 parts water)

Why does my liquid fertiliser smell? What do I do if it smells?

If the liquid produced by the HOTBIN smells fruity, acidic, or is pale yellow rather than dark brown these are good indicators you have excess water in your HOTBIN and the water is leaching intermediary organic acids out as it drains to the base. To stop the contents from turning anaerobic, you can remedy this by adding in extra shredded paper/cardboard to absorb the moisture and extra woodchip to provide additional aeration in the HOTBIN.

We do not advise you apply such liquid to plants. Many of these acids can be phytotoxic (bad for plants).

If you have black liquid or liquid that has a putrid or pungent drain like odour – the contents of your HOTBIN has gone anaerobic. We do not advise using this liquid either and you will need to correct the anaerobic contents, you can see how to fix an anaerobic HOTBIN here.

Will the liquid stain my patio?

Whilst the liquid may leave a brown mark on a patio, this will wash off in the rain or with a stiff brush (and washing up liquid if necessary) as it is water soluble. Please note you will often see small amounts of water and wetness around the base of the bin - especially in the morning - this is just the steam condensing and running down the unit and should not be confused with liquid seeping from behind the mesh plate.