Backflow stop valve: the key to preventing sewer back-up and flooding
Would you like to prevent basement flooding during major rainstorms? Have you had a sewer back-up event? By installing stop valves and creating a catch basin, you can prevent this kind of damage. Learn how to plan preventive work and details about funding.
Prevention is important
Each year, violent storms and torrential rain are becoming more intense and happening more often. Enormous quantities of rain falling and accumulating in the streets create more pressure than the municipal sewer network can handle. If your plumbing lines don’t have backflow stop valves or if they are incorrectly installed, wastewater can back up and flood your basement and garage.
Stop valve installation
Are stop valves installed in your home? If so, are they accessible? Are they in working order?
If your property has already flooded, or see sewer back-up, installation of a stop valve on each plumbing fixture is essential. And it’s mandatory according to municipal regulations. Since 2011, stop valves must be installed in all new buildings in Montréal.
Understanding how they work
A stop valve must be installed on the drain pipe of each plumbing fixture or group of plumbing fixtures in the basement. This means toilets, washbasins, shower stalls, washing machines, garage floor drains. Easy access to the stop valves is necessary for maintenance work.
Maintenance
Ideally, twice a year check that valves are in working order and not blocked.
Common problems
Some stop valves are installed at the wrong location or are worn out and no longer function. Rats may have chewed on them. On some properties, stop valves are hidden and access has been blocked since a floor has been laid, meaning their condition is unknown. It’s important to have a professional verify that your property is protected.
Creating a catch basin
Rainwater falling on your lot or the foundation drain can also cause damage in your basement. For better stormwater discharge, a sufficiently large catch basin must be created in your residence (minimum dimensions: 600 mm × 450 mm × 450 mm, or 24 in. x 18 in. x 18 in.). Include a pump to prevent overflow. Since major storms often lead to power outages, think about equipping your pump with a battery system. A stop valve will also prevent wastewater back-up.
Comprendre le fonctionnement
Un clapet s’installe sur la tuyauterie d’évacuation de chaque appareil ou groupe d’appareils de plomberie au sous-sol. Pensons à toilette, lavabo, douche, machine à laver, drain de plancher dans le garage. Prévoyez un accès facile à vos clapets pour les entretenir.
Entretien
Idéalement deux fois par année, assurez-vous que le clapet fonctionne et qu’il n’est pas obstrué.
Problèmes courants
Il arrive que des clapets soient installés au mauvais endroit ou trop usés pour bien fonctionner. Des rats peuvent les gruger. Pour certaines personnes, impossible de savoir où se trouvent les clapets et leur état, car l’accès a été bloqué par la pose d’un plancher. Prenez le temps de vérifier auprès d’un professionnel si vous êtes bien protégé.
Aménagement d’une fosse de retenue
L’eau de pluie provenant du terrain et du drain de fondation pourrait aussi générer des dégâts dans votre sous-sol. Pour permettre un meilleur écoulement de l’eau, une fosse de retenue assez grande doit être aménagée à l’intérieur de votre demeure (dimension minimum : 600 X 450 X 450 mm ou 24 X 18 X 18 pouces). Équipez votre fosse d’une pompe pour éviter les débordements. Comme une panne de courant accompagne parfois les épisodes d’orage violent, pensez à connecter votre pompe à un système de batteries. Un clapet empêchera aussi les eaux usées de refouler.
Work grant
Plumbing contractor
Contact a plumbing contractor that is a member of the Corporation des maîtres mécaniciens en tuyauterie du Québec (CMMTQ) for advice on the type of stop valve to use, and for installation and maintenance guidance. A plumbing contractor can also help you with the creation of a catch basin and all its necessary equipment. Once the work is finished, ask your contractor to give you a certificate of compliance with your bill.
Financial assistance
If you own a house or a building with 5 or fewer dwellings in Montréal, you can apply for a grant under the RénoPlex program for work to protect your building against flooding that costs more than $500. To qualify, the value of your residence must be less than or equal to $3,476 per sq. metre (learn how to calculate property value by square metre). Here are some examples of grant amounts:
- Installation of a normally closed back flow stop valve: $80
- Installation of a normally closed back flow stop valve, under an existing slab: $560 per valve
- Installation of a catch basin and a pump system: $1500
View Part 3 of the RénoPlex program to learn what types of work projects are eligible for subsidies
Full diagnosis and renovations
Problems related to the installation of gutters, flat roofs and countersloping garage entrances can also be corrected with the right work. View our article to learn how to determine what problem affects your home and to plan renovations to help prevent major damage.
Contact your local borough to find out what regulations apply in your area and what permits are required.
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