Grease and fat in drains is a nasty problem and can cause a lot of trouble for your drainage system. Blockages can cause your drain to back up, so when you experience heavy rainfall or have your washing machine running, you could find water flowing out of your drain and rain pipes and into the garden, street or even your windows and doors. We discuss where the grease and fat come from and how to clear it.

Where does grease and fat in drains come from?

Every time you wash pots and pans or use oil-based products in the bath or shower you deposit a small amount of grease and fat into the drainage system. When the water leaves the system, it works its way through traps (you can see these under your sink) and into the drainage system.

There is cold water in the trap and drain, so when the warm oil and fat hit the cold water, it solidifies. This solidified fat is tough and can set as strong as mortar when mixed with silt and debris. If the blockage is quite bad you can sometimes see the fat in your back drain, which will look like a dirty white rock – it can often smell sulphurous as well.

How to clear an outside drain blocked with fat

There are several homemade remedies that you can use to help break down the fat, including boiling water, baking soda and even a bottle of coke. However, this may only work if you have a partial blockage, meaning water is still trickling through. Let’s take a closer look at these methods:

Pour boiling water down the outside drain and kitchen drain

Boiling water will help break down blocks of fat when they are small and have not been left to build up over a long time. This will help you determine whether the internal pipes of the sink are blocked as well. Simply, pour the boiling water down the outside drain and kitchen sink (remember to remove strainer plugs beforehand). Repeat the process multiple times and see if there is any improvement in water flow.

Use baking soda and vinegar

Baking soda is sodium bicarbonate, and vinegar is made up of water and acetic acid. When combined, a reaction happens where molecules get exchanged, creating carbon dioxide and water that will bubble through the clog, breaking it up into loose material that can be flushed away. Using boiling water to flush the drain, will add pressure. Along with gravity, the pressure helps remove unwanted fat and sludge out of the pipes to unclog it the drain.

Use a bottle of coke

Coke contains phosphoric acid (that distinct taste that we know and love). It also helps prevent the growth of mold and bacteria in the sugary liquid. Pour a two-litre bottle of coke down a clogged drain and allow it to sit in the drain for at least an hour or two (or even up to 24 hours if the clog is severe). Then flush the drain with boiling water and repeat, as necessary.

Utilise drain rods

Drain rods which are available at DIY stores, can also help with unclogging the problem, as well as a plunger. It can often be worth trying these before calling a professional as the problem could be minor.

You can also purchase chemicals to break down the fat, however we advise using these with caution. They may work with nearby blockages – such as in the trap, but if the blockage is further down or outside you may find that this will not work. Some blockages could be as far as 10 metres (or more) down a pipe, which means a bottle of degreaser probably isn’t going to work.

How to prevent a drain from blocking

You can reduce the chances of your drains blocking by limiting what goes down your drain in the first place. Ensure that you have properly scraped your food off your plate before washing – that includes the dishwasher and try to limit how many oil-based products you use in the bath.

Coffee grounds can also be problematic, so make sure you scrape as many of the used grounds into the bin (or ideally onto your plants/soil as they contain lots of key minerals for plant growth) as possible before washing up your cafetiere.

If you have tried everything you can to remove the problem, but it’s not worked, then you will need to call a drainage professional who will be able to identify the problem and remove it. The Maintracts team are always here to help: 020 868 22244.