Domakihub Install a Waste Disposal Unit the Right Way
A step-by-step guide to fitting a kitchen waste disposer safely and correctly.
Reviewed by Domakihub home & decor pros · 2026-06-23 · 5 min read
A waste disposal unit grinds food scraps directly through your kitchen drain, keeping bins cleaner and cutting down on odours — a real advantage in holiday rentals and hotel apartments where turnover is high. The video above walks through a complete under-sink installation; the steps below give you the full process in plain language so you can plan the job before you start. Whether you are upgrading a Greek island villa or a city-centre apartment, the same fundamentals apply.
What Is a Waste Disposal Unit and Do You Need One?
A waste disposal unit (also called a food waste disposer or garbage disposal) is an electrically powered device that fits between the sink drain and the trap. A grinding ring and rotating plate reduce food waste to fine particles that flush safely into the drainage system. Most households find units of 0.5–1 HP adequate for daily cooking waste.
In Greece, municipal drainage networks in urban areas can handle disposers, but older rural or septic systems may need checking first. Always confirm with your local municipality or a licensed plumber before installing one if you are not on mains drainage.
Tools and Materials You Will Need
Gather these before you start: the disposer unit with its mounting kit, plumber's putty, a flat-head and Phillips screwdriver, adjustable pliers, a pipe wrench, Teflon tape, a bucket and towels (for residual water), and a voltage tester. You will also need a switched electrical outlet rated for the unit's amperage — or a hardwired connection via a dedicated circuit, which a licensed electrician should handle if one does not already exist.
How to Install a Waste Disposal Unit: 5 Steps
- 1
Prepare the Sink Drain Opening
Turn off the water supply and place a bucket under the P-trap. Remove the existing basket strainer by loosening the mounting nut from below the sink. Clean the drain opening thoroughly. Roll a rope of plumber's putty and press it around the underside flange of the new sink flange (the top piece that sits in the drain hole), then press it firmly into the opening from above.
- 2
Assemble and Lock the Mounting Ring
Working from below the sink, slide the fibre gasket, backup flange, and mounting ring up onto the flange's neck in the order specified by your unit's manual. Push the snap ring into the groove on the flange neck to hold everything in place. Tighten the three mounting screws evenly — use a screwdriver alternating between all three bolts to keep the flange level — until the putty squeezes out evenly around the top. Wipe away the excess putty.
- 3
Wire the Power Connection
If your unit uses a cord-and-plug, simply confirm the socket beneath the sink is switched (an air switch on the countertop is the safest option) and is on its own circuit breaker. If you are hardwiring, switch off the circuit at the breaker panel and verify zero voltage with a tester before connecting. Use wire connectors to join black-to-black, white-to-white, and green (or bare) to the ground lug on the unit. Tuck the wires safely into the unit's terminal box.
- 4
Mount the Disposer Body
Lift the disposer and align its three mounting tabs with the mounting ring slots. Rotate the unit clockwise until it locks into place and all three tabs are seated. Use the wrench (or the mounting wrench supplied) to continue turning until the unit feels firm and level. If a dishwasher drain will connect here, knock out the dishwasher inlet plug inside the unit with a screwdriver and remove the plug before hanging the unit.
- 5
Connect the Drain and Test
Attach the drain elbow to the side outlet of the disposer using the gasket and screws provided, then reconnect the P-trap and any dishwasher drain hose (a high loop to prevent back-siphoning). Restore the water supply, turn on the tap and check every joint for leaks. Finally, restore power, run a trickle of cold water, and switch on the unit — add a small amount of food scraps to confirm smooth operation. Cold water is essential: it solidifies fats so the blades can grind them cleanly.
Rather have a pro handle it?
Get a vetted plumbing pro in your city — one number, booked in EN/EL/DE.
FAQ
- Can I install a waste disposal unit if my property has a septic tank?
- It is not recommended without specialist advice. Disposers add significantly more organic load to a septic tank, which can overwhelm the bacterial balance and require more frequent pump-outs. Check with a local sanitation engineer before fitting one on a septic system.
- What size (horsepower) disposer do I need for a family home or rental?
- For a typical household or holiday rental, a 0.5 HP unit handles everyday food scraps (vegetable peelings, soft leftovers). A 0.75–1 HP model is better for larger families, high-turnover rentals, or if you regularly process harder waste such as small bones or fruit pits.
- Do I need a plumber or electrician to install a waste disposal unit in Greece?
- The mechanical plumbing connection is a manageable DIY task for a confident homeowner. However, if there is no existing switched outlet under the sink, you will need a licensed electrician to add one — this is a legal requirement in Greece for any new electrical circuit. When in doubt, booking a professional via Domakihub covers both trades in one visit.