Every item that enters your drain system either passes through cleanly, contributes to gradual buildup, or creates an immediate obstruction depending on its physical and chemical properties. A plumbing system that receives appropriate materials throughout its service life performs reliably and rarely needs emergency attention. A system that regularly receives grease, starchy waste, and non-dispersible materials accumulates blockages at a predictable rate.
Understanding the things to never put down the drain is one of the most practical steps a homeowner can take to protect their plumbing system and avoid emergency service calls. Galaxy Plumbing's licensed team has cleared blockages caused by every item on this list and has seen firsthand the damage that accumulates when drain habits go uncorrected. The guidance below reflects what professional plumbers across the GTA observe in drain lines every week.
This is the single most damaging category for residential kitchen drain lines. Cooking grease, rendered animal fat, butter, shortening, and cooking oil all appear liquid when hot and seem to drain away cleanly. They do not. As they cool in the drain line, they solidify and adhere to the pipe wall. Each pour adds to the layer. Over months, the internal diameter of the drain line narrows. Over the years, it closed.
Grease blockages are particularly difficult to clear because the material does not break up readily with snaking. Hydro jetting is frequently the only method that fully removes a mature grease accumulation from a kitchen drain line. The correct disposal method for cooking grease is to let it solidify in the pan, scrape it into the garbage, or pour it into a sealed container and dispose of it in the household waste stream.
Coffee grounds are a consistently cited cause of residential drain blockages. They do not dissolve in water and do not break down in the drain line. Instead, they accumulate at low points, bends, and any section of the line where flow slows, forming a dense sediment that other debris adheres to. Coffee grounds belong in the compost or the garbage, not the sink.
Pasta, rice, potato peels, and similar starchy foods continue to absorb water after they enter the drain, swelling and becoming increasingly adhesive as they do. Even small quantities that appear to rinse cleanly away with running water can accumulate at the trap or at any slight change in pipe diameter downstream. Combined with grease on the pipe wall, starchy food scraps form some of the most stubborn kitchen drain blockages a plumber encounters.
Eggshells do not dissolve in water and, when ground up, produce fine, sharp particles that adhere to greasy pipe walls and accumulate rapidly. They are among the things to never put down the drain if a garbage disposal is present: the disposal grinds them to sand-like particles that coat the interior of the line rather than flushing cleanly through.
Flour mixed with water forms a paste that coats pipe walls and attracts other debris. Rinsing baking bowls and dough-covered hands directly into the sink deposits this paste into the line, where it dries, hardens, and narrows the drain over time.
Products marketed as flushable wipes remain the leading cause of residential sewer line blockages related to flushed materials. The label is misleading. These products do not break down in water the way toilet paper does. They travel beyond the immediate drain section, accumulate at bends and junctions in the main sewer line, and form dense obstructions that trap other material. They are found intact inside drain lines years after being flushed. They belong in the garbage, not the toilet.
Cotton products do not disperse in water. They accumulate at drain traps and in the main sewer line, contributing to blockages and wrapping around any obstruction already in the line. These are things to never put down the drain or flush, regardless of their size.
Dental floss does not break down in water and is strong enough to bind other debris together inside the pipe. It wraps around partial obstructions, accelerates blockage formation, and, in drain lines with existing root intrusion, binds to root masses and increases their obstruction capacity.
Paper towels and facial tissues are not designed to disperse in water the way toilet paper is. They retain their structural integrity in the drain line and accumulate at bends and constrictions. Even in small quantities, regularly flushing these materials contributes to main sewer line blockages over time.
Hair is one of the most common causes of bathroom sink, bathtub, and shower drain blockages. It does not break down in water and binds with soap film to form dense mats at the drain trap and in the P-trap below the fixture. A drain strainer or hair catcher over bathroom drains eliminates most hair-related blockages without any additional maintenance effort.
Flushing unused or expired medication down the toilet or drain is one of the things to never put down the drain from both a plumbing and a public health perspective. Pharmaceuticals are not fully removed by municipal wastewater treatment and enter the water supply. In Ontario, most pharmacies accept unused medications through the Ontario's medication return program, which is the correct disposal channel.
d paint, turpLiquientine, mineral spirits, and household chemical cleaners should never be poured down any drain. These materials are often flammable, produce toxic fumes in the drain line, corrode pipe materials, and, for latex paint, solidify as they dry in the line. Many Ontario municipalities and regional waste management programs accept paint and chemicals at household hazardous waste collection events. Environment and Climate Change Canada provides guidance on the proper disposal of household hazardous materials.
Small amounts of diluted household bleach used in routine cleaning are generally safe for most drain line materials. Pouring large quantities of concentrated bleach, drain cleaner, or other caustic agents directly into drains is a different matter. These chemicals degrade older pipe materials, particularly cast iron and rubber seals, and create hazardous conditions for plumbers working on the line subsequently. They also interfere with the bacterial processes that break down organic waste in municipal wastewater treatment.
Even cat litter marketed as flushable is among the things to never put down the drain. The clay or silica compounds in cat litter absorb water and expand, blocking the drain line and creating a near-impenetrable obstruction. Cat litter belongs in the household garbage or in organic waste where accepted by the local municipality.
The consequences of routinely putting the wrong materials down the drain accumulate gradually and then present themselves suddenly. A kitchen drain that receives daily grease may run slowly for months before it stops entirely. A toilet that regularly receives wipes may flush normally for a year before a complete sewer line blockage produces a basement backup.
The cost of clearing a grease-blocked kitchen drain with hydro jetting, assessing a sewer line backup, and remediating any water damage is always significantly higher than the cost of changing a habit. Our Mississauga plumbers and Toronto plumbing team clear drain blockages caused by these materials regularly, and the pattern is consistent: the blockage was preventable.
If your drains are already showing signs of buildup, the right approach depends on the location and nature of the blockage. A kitchen drain slow from grease accumulation typically responds well to hydro jetting. A main sewer line partial blockage from accumulated wipes and debris requires camera inspection before the appropriate clearing method is determined.
Galaxy Plumbing's drain services cover everything from straightforward kitchen drain clearing to main sewer line assessment and restoration. Our team is available across the GTA for both scheduled drain maintenance and emergency clearing. If you are dealing with a drain that has stopped responding to reasonable clearing attempts, contact our team for a professional assessment.
For the environmental side of what goes down your drains, the City of Toronto's clear flow program and related municipal guidance explain the impact of residential drain habits on the municipal sewer and waterway systems.
Yes. Running hot water alongside grease delays the solidification slightly but does not prevent it. The grease cools as it moves through the drain line, and even if it passes the fixture trap, it adheres to the pipe wall further down the line where temperatures are lower. The hot water habit gives a false sense of safety and does not protect the drain from grease accumulation.
A garbage disposal grinds food scraps into smaller particles, but those particles still travel through the drain line and can contribute to blockages, particularly starchy, sticky, or fibrous materials. A disposal reduces the size of food solids but does not change the underlying drain chemistry. Grease, coffee grounds, and starchy scraps are things to never put down the drain regardless of whether a disposal is present.
Store-bought chemical drain cleaners can temporarily clear accessible, minor blockages, but they degrade pipe wall materials, particularly older cast iron and PVC, with repeated use. They are ineffective for deep-line blockages, create hazardous chemical conditions for plumbers working on the line, and are not appropriate for main sewer line problems. A licensed plumber using snaking or hydro jetting is a safer and more effective solution for any blockage beyond a minor, accessible trap obstruction.
Let cooking oil and grease cool and solidify completely. Scrape solidified grease into the household garbage. For larger quantities of liquid oil, pour it into a sealed container such as the original bottle and dispose of it in the household waste or at a local hazardous waste collection event. Some municipalities in Ontario also accept used cooking oil at specific collection points for recycling into biodiesel.
Yes. If your household has regularly disposed of grease, wipes, coffee grounds, or other problematic materials through the drain over an extended period, a camera inspection of the kitchen drain line and main sewer lateral provides a baseline picture of the current accumulation level. A plumber can assess whether clearing is advisable before a blockage occurs and recommend a maintenance interval to prevent emergency situations.
Galaxy Plumbing provides professional drain clearing and inspection services across the Greater Toronto Area. Whether your kitchen drain has slowed, your main line is showing symptoms, or you simply want to understand your drain system's current condition, our licensed plumbers provide honest assessments and clear recommendations. Contact our team today to request a free quote.
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