Vermifiltration mantainance

[Dahlia]

Hello everyone, im doing my phd and also have a small company all about nature based solutions and very focused on vermifiltration systems in Mexico. I have found different information about the maintenance and I’m unsure if 1) one should completely empty and refill the organic matter or wood chips from time to time, 2) how often the vermicastings should be recovered 3) what is the best method to do so and. 3) what type of wood shavings are you using ? I have read that pine shavings could contain phenols and resins which are not very good for earthworms and can decrease the pH, but I have use them with no problem so far but I would like to know which type of wood shavings are you using.. and finally 4) how often do you refiill the system.

Thank you so much for your help, I’m looking forward to rad from your expertises. 

[Kimi Ishikawa]

We have a pretty new system in the style of vermicompostingtoilets.net so I don’t have a track record yet, but my understanding is that it should never need emptying and you don’t harvest the vermicompost. You only add browns periodically to help balance the C:N ratio. The good stuff heads out to the drain field. That website has lots of good info on maintenance. My website BrownKawa.com also lists some other peer reviewed research papers in the FAQ and Resources sections. (My site is much more broad and does not hold a candle to Wendy Howard’s vermicompostingtoilets.net, but does have a little info on our system & those research papers that we used to get our permit.)

It does seem odd, because the water that comes out should be pretty clear, I think, so I don’t know what happens to the vermicompost. Maybe the microbes fully break it down into soluble stuff??

In any case, I hope that is how it works, because it would be a big mess and would disturb the whole ecosystem to dig down to the bottom of the IBC tote to access the vermicompost with fresh wastewater being added all the time? I suppose if you had a 2-tank system you could leave the unused tank to process for a while and then harvest… we have only had the need so far for one tank, and that’s all we anticipate needing.

My understanding is that some commercial systems in Australia had an auger-type system that would bring vermicompost to the surface, but I have also heard that some of their systems had problems with contamination and fell out of favor. I don’t want to risk any of that type of situation.

Re: materials… I live in a very dry piñon/juniper woodland, so only have those woods to work with. They work great. We used big branches, small branches, and filled in with chipper-shredded chips. So far we have topped off with straw or shredded cardboard, just because that’s what we have available. I supposed if you live in a place with lots of hardwoods, leaves, etc. you might have the luxury of being picky, but where I live everyone composts with pine and juniper and you should just use what is abundant in your area.

Good luck, and it would be great if you could keep us posted on what you learn!!

On Sun, Nov 30, 2025 at 6:52 PM Dahlia <dahlia.del...@gmail.com> wrote:

Hello everyone, im doing my phd and also have a small company all about nature based solutions and very focused on vermifiltration systems in Mexico. I have found different information about the maintenance and I’m unsure if 1) one should completely empty and refill the organic matter or wood chips from time to time, 2) how often the vermicastings should be recovered 3) what is the best method to do so and. 3) what type of wood shavings are you using ? I have read that pine shavings could contain phenols and resins which are not very good for earthworms and can decrease the pH, but I have use them with no problem so far but I would like to know which type of wood shavings are you using.. and finally 4) how often do you refiill the system.

Thank you so much for your help, I’m looking forward to rad from your expertises. 

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[Dean Satchell]

Hi Dahlia, welcome to the group.

Pine bark is the absolute best media, because it resists decay and you want a permanent substrate for the worms to live in that doesn't rot away. In contrast wood chips of the same size as pine bark decay very fast and wood shavings decay even faster. Once the humus builds up enough (from many years of use) this becomes the media, but until that happens your substrate needs to last the distance. I've found 20cm of pine bark does last the distance, whereas pretty much any other form of organic matter decays too fast and you risk not having sufficient substrate to filter properly, and it would be pretty messy to try and add to the substrate with a pile of fresh poos on top. Pine bark is usually available in different grades, for the primary vermifilter I use a fairly course grade.

Keep in mind that the primary vermifilter doesn't need to (and won't) remove all the solids. Suspended solids do make it through. This doesn't matter because if you have a soakage trench then the suspended solids decompose in that. Septic tanks usually discharge less suspended solids to the soakage trench than primary vermifilters, because septic tanks settle the solids rather than filter them. I settle the solids coming from the primary vermifilter and recirculate them back into the primary vermifilter, and follow with a secondary-treatment vermifilter so that I can discharge my treated effluent to the soil surface.

Always build twin primary vermifilters. This is important because you only want to remove humus from a well rested digester. Roundworm eggs take years to die, and composted faecal matter (lets call it humus) should not be put anywhere near gardens unless it is rested for a number of years. You shouldn't ever remove the bark/humus substrate, and I've found it unnecessary to remove any humus for at least a couple of decades. You can remove humus if you want to use it though... but again twin primary vermifilters are a must if you want to harvest humus, so you don't need to go near fresh poo. Eventually the single primary vermifilter will become a problem, even if that is someone else's.

Kind regards

Dean