Common Causes Of Blocked Drains And How To Unblock Them

Here are common causes of blocked drains and how to unblock them. 

Drains are simple devices that we rely on to work day in, day out, come rain or shine!

However, drains are prone to blockages which can cause issues ranging from nasty smells to full-blown floods. Keeping your drains in tip-top condition prevents blockages, but if you do experience one, it’s handy to know what to do. 

Here are common causes of blocked drains and how to unblock them. 

1: Blocked drains from hair

This mainly applies to shower and bath drains. Hair does not mix well with drains, especially when combined with soap, soap scum and soapy residues. Hair doesn’t degrade in drains and can build into a full-blown blockage that floods your shower

How to unblock drains from hair?

Firstly, invest in a quality hair strainer or hair trap that catches hair before it enters the drains. This is crucial to prevent future blockages. 

To unblock the drain, try a plumber’s snake - an implement you use to drill into the blockage and dislodge it. Use a coat hanger as a DIY substitute if you don't own a plumber’s snake. You can pry and pull the hairy blockage from the shower by fashioning the hanger into a hook and inserting it into the drain. 

Failing that, you can buy shower drain cleaners that are specifically designed to tackle hair. For example, Mr Muscle offers one here.

2: Blocked drains from dirt

Dirt typically blocks outside, and kitchen drains but can block interior drains too (be careful washing muddy legs in the shower or bath!)

Outside kitchen drains often become blocked by mud, dust, moss and other particles that fall into the drain. The process for unblocking a dirty outside drain differs from an inside drain.

How to unblock drains from dirt? 

If your interior drains are blocked from dirt, try flushing them with boiling water first. Then, drill down into them using a plumber’s snake or coat hanger. 

Failing that, try adding half a cup baking soda followed by half a cup vinegar. If those fail, move on with specialist drain cleaning products that you can buy from supermarkets and hardware stores. 

You may need a drain rod if your exterior drains are blocked by dirt. A drain rod is a larger, more robust version of a plumber’s snake. 

Drive the rod into the drain to locate the blockage and dislodge it. You can also try boiling water, vinegar and baking soda and outside drain cleaners. Outside drain cleaners are more powerful than those used for interior drains.


Engineer cleaning out door drain

3: Blocked drains from food

When it comes to the kitchen sink, food is the number 1 culprit for drain blockages. Blocked sinks often flood and regurgitate food.

flooded kitchen sink
Above: Flooded sink

Firstly, it’s wise to invest in a decent kitchen sink strainer to prevent food from entering the drain in the first place. 

To avoid blockages in your kitchen sink, don’t flush the following foods down the drain: 

  • Cooking oil and fat
  • Burnt food 
  • Dairy 
  • Flour or grain 
  • Eggshells
  • Rice
  • Potato 
  • Pasta 

Generally, anything tough and starchy shouldn’t go down the drain. 

How to unblock drain from food?

To unblock your kitchen drain, firstly, try to flush it with hot and boiling water. This might cause the sink to flood, in which case you’ll need to remove the standing water before continuing. 

Next, try a plumber’s snake. Manoeuvre it into the drain to feel the blockage, drill into it, and dislodge it. You can also try baking soda with vinegar and purpose-made kitchen drain cleaning products. Another useful tool is a sink plunger, a small version of a standard toilet plunger.

If all else fails, detach the trap U-bend from under the sink and clean it. If that still doesn’t fix the issue, the blockage may go further down in the plumbing - consider calling a plumber. 

4: Blocked drains from heavy rain and storms 

Heavy rain can cause blockages to outdoor drains in a few different ways. Firstly, rain can flood the plumbing system, which causes overflows and flooding, which can last for days. Secondly, water forces dirt, leaves and debris into drains, causing blockages. 

Thirdly, water pressure can crack pipes and cause internal issues that increase the odds of blockages. Again, this typically only affects outside drains, which are your responsibility if they’re on your property. 

How to fix blocked drains from heavy rain and storms 

The first port of call should be using a drain rod to try and dislodge the blockage. Drain rods can extend into the drain and are effective at dislodging most physical blockages. Outside drain cleaning products may help soften the blockage. 

If that fails, you can use a pressure washer with a drain cleaner attachment. You can find drain cleaning kits for most major pressure washer brands such as Karcher. You can also try a garden hose, as below. 

Cleaning outside drain with red hose
Above: Cleaning outside drain with garden hose

5: Blocked drains from broken pipes

Broken pipes are rare, but can cause serious issues and expenses. Moreover, your local council authority can order you to repair or unblock a private sewer or lateral drain if they deem that it's not properly maintained.

Diagnosing broken pipes is not easy and will likely involve ruling out other blockages unless you can physically see the breakage. 

How to unblock drains from broken pipes

If you suspect a broken pipe, your best bet is to call a plumber or drain repair service. They’ll be able to diagnose the issue, using cameras and other technology if necessary. Most broken pipes are straightforward to fix. 

6: Blocked drains from toilet paper

Modern toilet paper is often thick and quilted, which has made blockages much more common. 

Not all toilets and plumbing systems are designed to withstand these sorts of toilet paper, so if your toilet is getting blocked regularly, check your paper to ensure it’s not excessively thick! 

Blocked toilet with wooden toilet seat in pink tiled bathroom
Above: Blocked toilet

How to unblock drains from toilet paper

The plunger is the first port of call for unblocking toilets. You can use a plunger on flooded toilets too, which is great if there’s lots of standing water. Standard plungers are easy to use - simply place them over the toilet and plunge away. 

Water jet plungers are similar but allow you to suck water from the toilet and spray it down to forcibly remove blockages. 

There are plenty of toilet cleaning products that soften toilet paper, but vinegar and baking soda usually work well. Add the baking soda first and combine it with a similar volume of vinegar. 

7: Blocked drains from mineral build-up

Hard water areas often suffer from mineral and limescale build-up in pipes and drains. Mineral build-ups can worsen other blockages that involve soap scum and hair. 

How to unblock drains from mineral build up

Mineral build-up is often clearable with boiling water. Otherwise, try white vinegar left overnight, and then attack the blockage with boiling water. You can squirt the water from a bottle to increase the pressure (be careful if it’s hot, though). 

Mixing warm water with washing powders can also help remove mineral buildup. However, if that fails, there are plenty of general cleaning products, such as the Mr Muscle Foam Cleaner, designed to remove mineral build-ups and limescale. 

8: Blocked drains from foreign objects

Foreign objects can fall into drains and block them or act as a catch to cause a blockage from debris that builds up around the object. Pretty much any non-degradable object can block a drain, including toothpicks, plastic cutlery, paintbrushes and bits of plastic. 

Wet wipes, cleansing wipes, sanitary towels and other non-degradable papers, clothes and fabrics also commonly block drains. For outside drains, common culprits include sticks, twigs and stones. 

How to unblock drains from foreign objects

You’ll usually need to disassemble the plumbing to remove a foreign object. In the case of a kitchen sink U-bend, this is relatively straightforward. However, in the case of a shower, bath or outside drain, removing the object may be tricky. 

In some cases, it might be possible to remove the object with a long grabber, sometimes called a gulley grab. Softer foreign objects such as wet wipes can be removed with a plumber’s snake or drain rod. 

If you can’t see the object, then a plumber or drain repair service will need to diagnose the issue by ruling out other forms of blockages and removing the foreign object professionally. 

Summary: Common causes of blocked drains and how to unblock them

There are many causes of blocked drains, but luckily, most are straightforward to solve. As a rule of thumb, try the easier methods first before stepping things up and using drain cleaning products. 

If your drains frequently become blocked, consider investing in a plumber’s snake or drain rod. When cleaning your drains, be careful not to cause additional damage as this could worsen the issue. 

If the fixes contained in this article don’t work, the next step is to call us. Plumbers or professional drain cleaners will accurately diagnose the fault and fix any underlying issues that are causing frequent blockages. Explore our drainage insurance to ensure any problems are quickly resolved.

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