If you are budgeting for a new fit-out or trying to stay compliant with City of Cape Town wastewater bylaws, understanding grease trap prices is the first step. A grease trap (also called a fat trap) intercepts fats, oils and grease (FOG) before they reach the sewer line, where they harden, cause blockages and trigger expensive callouts. Pricing varies widely depending on the unit size, whether it is a domestic or commercial installation, and how often it needs to be cleaned.
This guide breaks down what you can expect to pay for grease trap supply, installation and ongoing servicing in South Africa, with practical sizing advice for restaurants, takeaways, butcheries and small kitchens.
What is a grease trap and why do you need one?
A grease trap is a passive chamber installed between your kitchen drains and the municipal sewer. As warm wastewater enters, the trap slows the flow so that lighter fats and oils float to the top while heavier solids settle to the bottom. Only the clearer water in the middle exits to the sewer. Without this separation, FOG cools inside the pipe, hardens like wax, and eventually causes the kind of blockage that puts a commercial kitchen out of business for a day or more. For background on why this matters, see our overview on causes, effects and solutions for blocked drains.
Grease trap prices by type
Domestic grease traps
Small under-sink units suitable for a private home or guest house typically cost between R2 500 and R6 500 for the unit itself. They handle low flow rates (around 30 to 50 litres per minute) and a single sink. Installation is straightforward and adds roughly R1 500 to R3 500 depending on access and plumbing changes.
Commercial grease traps
Restaurants, hotels, school kitchens and food manufacturers usually need larger units sized to peak flow. Expect:
- Small commercial units (50 to 100 litre capacity): R8 000 to R18 000 supplied
- Mid-size units (200 to 500 litre): R20 000 to R55 000 supplied
- Large in-ground interceptors (1 000 litres and up): R70 000 to R180 000 plus excavation
Installation on commercial sites adds civil work, plumbing tie-ins and sometimes excavation. A simple above-ground retrofit might cost R6 000 to R15 000, while an in-ground interceptor with concrete work and re-routing of waste lines can push installation to R40 000 or more.
How to size your grease trap correctly
Buying too small is the most common (and expensive) mistake. An undersized trap fills with FOG within days, overflows into the sewer, and you end up paying for both servicing and the blockages you were trying to avoid. A rough sizing rule used by Cape Town plumbers:
- Add up the volume of all fixtures discharging into the trap (sinks, dishwashers, woks).
- Multiply by 0.75 to account for partial filling.
- Divide by 2 (the retention time in minutes) to get the required flow rate in litres per minute.
- Choose a trap rated for that flow with at least double the static capacity.
If you are unsure, our team will size it on site at no charge before quoting. For the regulatory background on sizing, see our guide to grease trap regulations in South Africa.
Grease trap cleaning costs
The purchase price is only the start. By law and by good practice, every trap needs scheduled cleaning to stop FOG escaping into the sewer. Typical Cape Town pricing for routine servicing:
- Under-sink domestic unit: R450 to R850 per clean
- Small commercial trap (under 200 litre): R900 to R1 800 per clean
- Mid-size trap (200 to 1 000 litre): R1 800 to R4 500 per clean
- Large in-ground interceptor: R5 000 to R12 000 per clean
Most restaurants need their trap serviced every four to eight weeks, while high-volume kitchens may need fortnightly visits. Skipping cleans almost always works out more expensive than the cleaning itself once you factor in emergency callouts and lost trading time. We cover this in more detail on our grease trap cleaning frequency guide.
What affects the price you pay?
- Material: PVC and polyethylene units are cheaper than stainless steel or concrete interceptors, but have shorter lifespans in high-temperature kitchens.
- Access: Traps in basements, under counters or in tight courtyards take longer to service and may carry an access surcharge.
- Disposal: Waste must be taken to a licensed treatment facility under the Western Cape Waste Management Act. Disposal fees are usually built into the cleaning price, but always check.
- FOG load: A trap that has been neglected costs more to clean the first time because of compacted grease.
Common problems that drive up costs
Most cost overruns trace back to a handful of avoidable issues — missed service intervals, undersized units, and disposing of solid food scraps through the sink. Our breakdown of the five most common grease trap problems covers what to watch for. If you are still deciding which type of trap suits your kitchen, this guide walks through the options.
Get a tailored grease trap quote
Every kitchen is different, and a published price list cannot replace a site visit. Drain Blasters supplies, installs and cleans grease traps across Cape Town and surrounding areas, with a free on-site sizing assessment for new installs. For more on our commercial servicing, see grease trap cleaning Cape Town. To request a quote, head to our contact page or call us during business hours.
For the underlying compliance framework, the City of Cape Town’s wastewater bylaw is available on the official City of Cape Town water and sanitation portal.
