The Heatwave's Over; But It's Not All Good News...

With Sadiq Khan saying that he is 'seriously concerned' about the potential for severe surface water flooding in London following last Friday's official announcement of a drought, today's forecasted rain may not be the relief we had all been hoping for. But what can you do to protect yourself and your property from flash flooding in a city that's largely 'underprepared' for what's to come?

DrainGuard, by Crownstone, is your solution.

The Problem

On 12th July 2021, 76mm of rain fell in London in just 90 minutes, leading to widespread flash-flooding on the wettest day in over 37 years. When several flood events of similar magnitude occurred repeatedly in a period of just under 2 months, it was clear that this was no freak event but something the UK needed to brace itself for, as the effects of climate change begin to be ever-more glaringly obvious in the world around us. Within many cities, the design and construction of drainage system infrastructure lagged behind population growth. The inner London ‘Victorian’ drainage system was designed for a city of four million, but now has to service a population of nine million and is 80% full even during dry periods. And when the system becomes overloaded, the hygiene issues arising from inundation with both rainwater and sewage are acute. As experts in drainage and residential flood prevention matters, Crownstone were called in by the owners of several West London townhouses, not only looking for a solution to the imminent issue of flood damage, but a long-lasting solution to protect themselves and their property. With insurers suffering aggregate losses of over ￡100m in London residential flood claims in just 2 weeks, it wasn’t just safety and comfort on our clients’ minds, many had been told that unless they took direct action to reduce the risk of inundation to their property, their insurance premium would rise by up to 2000% the following year. But it’s important to remember that some of our most valuable possessions have no insurable worth whatsoever: basements are often used for storage and whilst an insurance pay-out may cover the costs of replacing a few mid-range storage boxes, there can be no price placed on the childhood photo albums which are so often irrecoverably damaged. Crownstone brought 20+ years of expertise in drainage and basement design to the table, to devise an innovative and fully-compliant solution but the challenges and considerations were not insignificant.

The DrainGuard Solution

As structural waterproofing experts, we know that the drainage systems so commonly used in basements often do not comply with BS8102: 2022, with key parts of the system being overlooked: drained systems are typically vulnerable to pump failure and/ or other elements of the drainage system backing-up behind the waterproofing, either due to insufficient maintenance or insufficient capacity during storm events. We also know that, in accordance with BS8102:2022, any increased severity or frequency of storm and flood events may affect the use of the space going forward: in short, if it’s not dry, it’s not habitable. In addition to this, failure to make the existing conversion BS8102: 2022- and BS8301 (Drainage and Waste Disposal)- compliant may also affect the outcome of any future insurance claims relating to flooding as a result of storm events, with insurers placing ever more restrictive covenants on basement and flood coverage. In response to this set of demands, Crownstone designed and installed, DrainGuard, a system developed in such a way as to prevent the ability of sewage to back-up in channels to the extent that inundation occurs and the property is compromised. DrainGuard by Crownstone:

1) Uses a combination of non-return valves and mechanisms to ensure that sewage from the main run cannot track backwards towards the property;

2) Features a pumped overflow system, using foul with capacity to work against the head of pressure, during periods of inundation, forcing water back into the main run, past the non-return valve and against the head of pressure and preventing the property from being flooded with its own sewage;

3) Allows the system to pump against the head of pressure to cope with household usage during a storm event.

The Result

With climate change, increased population density and continued building on impermeable surfaces, these kinds of flash-floods are certainly not a problem which are going to ‘fix themselves’ any time soon. However, with the implementation of DrainGuard, Crownstone has taken a massive step forward in protecting our clients, their properties and, often most importantly of all, their memories, providing peace of mind that the issue of flooding is not only severely mitigated, but that their basements are fully-compliant and remain fully-insured, without unaffordable premium?hikes and the risk of cancelled cover later down the line.

For more information, contact Crownstone today on 0208 226 5654 or email [email protected].

Crownstone. For wherever you don't want water.