Check drainage systems as extreme weather eases, advises Catalyst

The UK is expected to emerge from a big freeze this week.

But climate change means homes are more likely to be affected by floods than blizzards in the years ahead, with implications for drainage maintenance, says Catalyst Services UK Operations Director Paul Duddle.

Plummeting temperatures, ice and snow, and their impact on issues like travel and heating bills have been in the news for days. But volatile weather and heavy rain triggered by global warming is likely to be the more significant long-term story.

“The risk of flooding will be the key issue during winter in the UK in the coming years. Indeed, the floods in Greater Manchester and on other areas this month make that clear,” explained Paul Duddle.

“This has serious implications for management of drainage systems, both in terms of planned maintenance, to prepare them for heavy rain, and reactive maintenance after flooding has occurred.”

With this in mind, Catalyst’s drainage experts recommend that property owners in areas affected by flooding, even where it is relatively localised, should consider carrying out a number of maintenance checks in the coming days.

Check for blockages and debris accumulation

Flood waters can carry silt, soil and vegetation debris into surface water and sewer pipes, increasing the risk of blockages. Make sure drain gullies are clear and look out for signs of blockages, including slow draining of pipes.

Culverted water courses running through, or close to, properties should also be checked. Debris can build up on pipe grates and culverts can be clogged with silt. This could increase flood risks the next time it rains heavily, unless the culvert is cleaned.

If rain water is pooling on lawns or driveways, or foul pipes are draining slowly, consider having the drainage system professionally cleaned to remove blockage material and restore its capacity.

• Look out for structural damage
  High water volumes in drains and sewers can result in pipes, possibly already weakened by minor faults, becoming seriously damaged. Problems can include cracking, displaced joints and pipe collapses.
  Again, if there are signs of drainage systems not working as they should, a sensible response is to commission a drainage specialist to carry out a CCTV drainage survey to identify the location and scale of any problems.

• Consider installing non-return valves
  Non-return valves, also known as backflow valves, are devices installed in drains to prevent sewage from backing up in a pipe and entering homes through sinks, baths or toilets.
  In their simplest form, they have flaps that allows water to flow in one direction but shuts if it is pushes back up the pipe.
  If a home or business owner is concerned that their property could be at regular risk of flooding, they should consider having non-return valves installed in their drainage system.
  Though they cannot prevent surface water flooding, if fitted properly, they will stop water entering properties through the drainage system.

• Have a flood emergency response plan
  Climate change is predicted to increase the flood risk for millions of homes across the UK. Property owners should assess the flood resilience of their homes or businesses, or have measures in place to minimise damage, for example by installing barriers, building with flood-resistant materials, or moving valuable items above expected flood water levels.

Flood risks to off-mains drainage systems

Heavy and prolonged rain and flooding can also adversely affect off-mains drainage systems, such as cesspools, septic tanks and sewage treatment plants, plus associated facilities, such as drainage fields.

• Prolonged rainfall can cause the water table around an off-mains system to rise, resulting in its drainage field becoming saturated, so wastewater backs up in the tank.
• Surface water can infiltrate off-mains drainage tanks, for example through manhole covers or cracks in pipes, taking soil and silt with it.
• This can reduce the tank’s capacity, and disrupt the filtration system, resulting in solid material blocking inlet or outlet pipes.
• If the system has a drainage field, these solid materials and silt could clog it too, or water from a flooded drainage field could flow back into the tank.
• This will stop the off-mains system working properly, increasing the risk of sewage backing up into a property or seeping out onto surrounding land, creating a serious pollution risk in both cases.

Off-mains systems – response to flooding

During a flood event like this, the property owner should do all they can to minimise the pressure on the off-mains drainage tank by minimising water usage.

As soon as possible afterwards, they should call in a drainage specialist with off-mains drainage expertise to inspect the system and carry out any work needed to ensure it is working optimally once more.

It is not advisable to empty off-mains drainage systems, especially older ones, while groundwater remains high, as the pressure on the tank could result in it being damaged.

Prevention better than cure

Paul Duddle said: “As a drainage specialist delivering services for insurance clients and their customers, Catalyst has a great deal of experience of responding to these urgent issues.

“For example, we regularly respond to claims made by home owners in flooding hotspots like Carlise in Cumbria and along the River Severn in Worcestershire, Herefordshire, and Gloucestershire.

“Our work involves flushing drains after flooding, inspecting sewers and off-mains drainage systems for damage, and putting in mitigation measures, such as backflow valves, to reduce future flood risk.

“We can also help property owners minimise risks caused by flooding, for example by reviewing the capacity and condition or drainage systems. The cost of being prepared is always much, much less than the cost of damage caused by flooding.”

Find out more

Talk to Catalyst today about inspecting drains, sewers and off-mains drainage systems after flood events and flood damage prevention measures.

Telephone: 0333 004 8008. Email: [email protected].