Used cooking oil and kitchen grease occupy an odd space in most waste conversations — too liquid to bag like general waste, too specific to fit our organic composting stream, and, if poured down a drain, a genuine contributor to the same drainage blockages we've written about elsewhere. A handful of small eateries in Kasarani approached us about this specifically, and it's become a small but growing thread of our commercial waste work.
Why used cooking oil is a distinct problem
Unlike solid food waste, used cooking oil doesn't decompose the way organic scraps do, and it isn't safely absorbed by soil or compost the way plant matter is. Poured down a drain, it cools and solidifies inside pipes, contributing to blockages in exactly the kind of drainage infrastructure we've highlighted as a flooding risk in our short rains preparedness work. Poured onto open ground, it contaminates soil and creates a slip hazard, and burned, it produces heavy smoke and particulate pollution beyond what burning solid waste already causes.
How small eateries have traditionally handled it
In the absence of a clear disposal route, most small eateries in Kasarani have historically handled used cooking oil in one of a few ways: reusing it repeatedly well past a safe or hygienic point, pouring small quantities down drains gradually rather than in one obvious dump, or, less commonly, selling small volumes informally to buyers who repurpose it for other cooking uses, a practice with genuine food safety concerns we don't encourage.
What our collection arrangement offers instead
We now collect used cooking oil from a small number of participating eateries on a scheduled basis, storing it separately in sealed containers rather than mixing it with any other waste stream. Collected oil is passed to buyers who process it into other uses — certain industrial and soap-making applications can use used cooking oil as an input, provided it's collected before it degrades too far or becomes contaminated with food debris.
Why we started small and haven't scaled this quickly
Used cooking oil handling requires specific storage — sealed containers, careful transport to avoid spills — that differs meaningfully from our standard collection equipment. We deliberately started with a small number of eateries to work out these logistics properly before expanding, rather than promising a broader service we weren't yet equipped to deliver reliably. This mirrors the same cautious, pilot-first approach we used before adding a full recycling bin rollout in Hunters.
What eateries have said about participating
Participating eateries describe the main benefit as simply not having to think about the problem anymore — used oil that used to accumulate awkwardly or get disposed of in ways owners weren't entirely comfortable with now has a clear, scheduled outlet. A couple of eatery owners have also mentioned that customers occasionally ask about their environmental practices, and having a proper cooking oil disposal arrangement is a small but genuine answer to that question.
The connection to drainage and flooding
This work connects directly to our broader concern about Kasarani's drainage system. Used cooking oil poured down drains, even in modest quantities, contributes to the same blockage patterns that dumped solid waste causes, and it's a contributor that's easy to overlook because it doesn't look like "waste" the way a discarded bag or bottle does. Expanding proper cooking oil collection is, in a real sense, an extension of our drainage preparedness work, addressing a less visible but still significant source of the same underlying problem.
What we're considering for the future
We're exploring whether demand exists to expand this beyond our initial small group of eateries, potentially including household-level cooking oil collection for residents who cook with larger quantities regularly. As with our commercial hardware shop partnership, growth here will likely depend on developing a clear, sustainable pricing and logistics model before expanding the service broadly.
What a typical collection visit looks like
Our team visits participating eateries on a set day, exchanging a full sealed container of used oil for an empty one, so there's no gap in the eatery's ability to safely store oil between visits. It's a simple swap system, deliberately kept low-effort for the eatery, since asking a busy kitchen to manage complicated storage or scheduling around this service would undermine the whole point of removing a burden rather than adding one.
Frequently asked questions
Can any restaurant or eatery in Kasarani join this programme?
We're currently working with a small number of participating eateries while we refine the logistics; if you run an eatery interested in joining, reach out to discuss whether it's currently feasible for your location.
What happens to the used cooking oil after collection?
It's passed to buyers who process it for other industrial or soap-making uses, rather than being disposed of as general waste.
Is it safe to pour small amounts of cooking oil down the drain?
No. Even small amounts contribute over time to blockages in drainage systems, the same pattern that drives seasonal flooding risk elsewhere in Kasarani.
Read more about how blocked drains connect to flooding risk in our piece on short rains drainage preparedness.