Why Do Drains Backup When It Rains? Causes and Prevention Tips

The Great British weather often leaves much to be desired with strong winds and heavy rainfall causing chaos across the country. Heavy rainfall can often be exacerbated by drains backing up, leading to slow-draining sinks, gurgling noises and even flooding. Not only is this frustrating but it can be damaging and potentially dangerous.

Understanding the reasons behind rain-related drain backups can help homeowners take preventive measures and avoid costly repairs and accidents. At Drain Doctor, we are always looking to help our customers save costs on their drainage repairs. We offer 24-hour drainage and emergency plumbing fixes and callouts to address the problem quickly and efficiently before issues worsen.

In this article, we explore 5 common causes of drain backups when it rains and our tips for preventing this in the future.

Why do my drains back up when it rains?

1. Your sewer system has been overloaded

During particularly heavy rain, sewer systems can reach capacity. If the system can’t handle the excess water and has nowhere else to go, it can cause backups in homes that are connected to the main sewer line. To find out whether your home is connected to a main sewer line you can check your property deeds, consult your local council or contact a drainage specialist who can perform a CCTV drain inspection survey.

2. Clogged and Blocked Pipes

Over time it’s very common for debris, leaves, and grease to accumulate in household drains and sewer systems. These blockages prevent water from freely flowing through the pipes. When rainfall meets the blockage, it can quickly overwhelm the system leading to backups in your home or on the street outside.

You may find that drains become blocked after heavy rain as more debris and litter is swept from the street into storm drains and surface drains.

3. Invasive Tree Roots

Tree roots can spread distances of up to 3x the height of the tree and will naturally seek water sources. Unfortunately, this makes sewer systems an ideal target for growing roots. The roots could lie within the pipes without detection for a number of months, you’ll only realise they’ve taken root when you start experiencing drain backups. When it rains, the moisture increases which causes the roots to grow and further obstruct pipes.

4. Damaged, Broken or Collapsed Pipes

Older or damaged pipes can collapse through ground erosion, which restricts the flow of rainwater and causes backups. Pipes can become damaged due to shifting of soil, corrosion, debris and tree roots, or heavy vehicle traffic directly above underground pipes. With above-ground pipes, such as your guttering and drain pipe you may be able to visually identify damage but underground systems are much more complex. A CCTV drain survey is the best and only way to understand the condition of your drain system and identify broken and collapsed pipes.

5. Ineffective Garden Drainage

If you notice it’s primarily your basement drain backing up after rain, it’s likely that your garden is not draining water away properly. This can cause water to seep into the foundation of your home which could cause basement or ground floor flooding. Poor garden drainage also puts a lot of pressure on drain systems which could cause further issues throughout the rest of your home.

How can I prevent my drains from backing up?

Regular Drain and Sewer Maintenance

It’s a common and costly misconception that drain systems don’t require any ongoing maintenance. There’s some simple at home maintenance you can carry out within your home to help maintain the condition of your drain system.

However, professional maintenance, cleanings and repairs are still necessary for your drainage system. Routine inspections will allow for early detection and removal of debris and blockages. They will also identify areas of the system that are starting to show signs of wear and tear, that may need repairing or replacing, as well as being able to complete the correct repair and replacement to a high standard.

At Drain Doctor, we offer extensive drain camera surveys that can provide you with information on the effectiveness of your current drain system, identify any blockages and damages that could cause harm during future rain. Before purchasing a property, we would recommend a homebuyer drain survey as this will uncover any potential drainage issues. After completing a CCTV drain inspection Drain Doctor will provide a detailed drain camera survey report that is accompanied by repair recommendations.

Carried out pre-purchase, our CCTV surveys are also popular with sellers who are then able to sell with confidence and assure the buyer that any problems are resolved or highlighted.

Cleaning your Gutters and Downspouts

It’s important to keep your gutters and downspouts free of leaves and debris to ensure water can freely flow away from your home’s foundation and drains. Strong winds and small animals can both contribute to debris gathering in your gutter, when it rains this can all be pushed down your drainpipe and through the downspout causing water to pool.

We would recommend speaking with a professional to have your gutters and downspouts cleared regularly as they’re already trained and confident working at a height and will have the right equipment for keeping them blockage-free. Many window cleaners will already offer a gutter cleaning service or alternatively, you can speak to a drainage specialist like Drain Doctor.

Avoid Using Non-Flushable Items

The most common blockages we see within drain systems are wet wipe, feminine hygiene products and baby nappies, none of which are suitable for flushing. These products are not manufactured with materials that properly breakdown in water, instead they start to build up within the sewer system until they cause a huge blockage which can cause your plumbing to back up. All waste needs to be disposed of correctly and responsibly. Adding a small bathroom bin with a lid next to the toilet is the best way to dispose of these additional products.

What You Pour Away Matters

The kitchen sink and shower are two areas that commonly struggle to drain, cause backups or are guilty of clogging the system. Using a simple debris catcher in your kitchen sink can prevent food from blocking your pipes, they’re very inexpensive but make maintaining your plumbing much simpler. Just make sure to empty out any food debris into your food waste or compost bin. You should never pour grease down your sink, you may think it’s fine because it’s a liquid but once cooled it starts to solidify, forming a sticky trap for dirt and debris, leading to tough blockages.

Shower and bathtub drains are typically very hair-prone, this hair starts to matt together in the pipes forming large clumps that prevent water from properly draining away. These clumps can also be pushed further through the system combining with other debris – making for a nasty blockage. Adding a hair catcher over your plug hole in the bath or shower can completely prevent this.

Address Tree Root Issues

If you know there are large trees near your sewer lines, it would be sensible to consider a CCTV drain survey to identify whether damage from the roots has already been done. If it has your professional drainage team will work to remove the roots from the pipes whilst repairing and replacing any areas that require it.

If they’ve not started causing damage but you’re worried they one day might, you could consider speaking with a local tree surgeon for advice or root removal. Alternatively, you can contact Drain Doctor and we can assess the current situation and provide proactive solutions to protect your drain system and prevent any backups during the rain.

Improve Garden Drainage

To improve garden drainage, consider installing practical solutions like French drains, soakaways, or gravel trenches to redirect excess water. Raised beds and sloped landscaping can help prevent water from pooling in low-lying areas. If you find your garden is often waterlogged during rain, it will benefit you to speak to a professional gardener or drainage and plumbing expert who can assess the current condition of your garden and discuss reasonable solutions.

Need to Speak to Professional Drainage and Emergency Plumbing Experts?

Rain-related drain backups can be a serious problem, leading to costly water damage and drainage repairs. Understanding the causes and taking preventive steps can help keep your drainage system functioning properly. Contact Drain Doctor for a free callout and a free no-obligation quote.

Alternatively, you can book your CCTV Drain Survey today!