How to solve flooding issues in your basement during heavy rainfall

The National Disaster Management Authority of India may have considered natural events like rainfall and storms as meteorological factors causing urban flooding while soil moisture level, surface infiltration rate are some of the hydrological factors doing the deed. But the longest list of causes is full of anthropogenic activities, one classified as ‘human factors’, such as urbanisation, deforestation, occupation of flood plains, the inefficiency of the stormwater drainage system, non-maintenance of infrastructure, climate change, indiscriminate disposal of solid waste, absence of sewerage, extreme precipitation, among others.

Urban flooding has caused billions of dollars worth of damage to property in recent years and has given even the most proactive homeowners (as well as the government) sleepless nights. Everyone is a part of the problem and very few strive for solutions. While the collective works gradually towards larger, city-wide and community-based approaches, this article will help you get familiar with individual techniques and workarounds you can use as a flat owner or member of the Managing Committee, when flooding gets severe enough to threaten and destroy the basement level of your apartment (ground floor or underground). This will at least check off one of the human factors causing urban flooding- “non-maintenance of drainage and infrastructure”, and give you an understanding of preventive measures to stop flooding as well.

Sump pump installation and maintenance

If your building is prone to rainwater damage and excessive flooding, your best bet would be to install a sump pump in the basement. These are basins/ puts dug inside the foundation where the water is collected and a sump is attached which throws the water away from the basement and transports it through a pipe to a dry well, water body or municipal storm drain. You can get a fully automatic sump pump instead of a manually operated one if the flooding gets out of control every monsoon. It’s advisable to get an automatic sump pump with a battery backup so that the pump can work even during power outages. Sump pumps also help reduce dampness, mold and mildew from your basement as they don’t let water accumulate. They should be maintained by removing debris, dirt, and other obstacles, and the valve should be examined so it’s not jammed.

Box-type basement waterproofing

This type of waterproofing is specially used only for basements. In this system, limestone slabs (known as Shahabad stones in India) are laid down along with wire brushing, crack filling with rich mix cement, filling the joints with grouting and integral plasticizer, with proper compaction to reduce cracks and facilities for diversion of water. The curing period can be between 7 and 15 days. This service can cost between Rs 25 and Rs 40 per square feet. This is a common method but it’s time-consuming so some societies opt for crystalline waterproofing (growing crystals inside concrete) or liquid membrane (liquid sprayed by brush or roller in concrete) waterproofing. Some societies also prefer exterior wall waterproofing so that there’s no structural dampness.

Maintenance of drains and water spouts

During the monsoon, the main reason for flooding is ill-maintained drainage. As a preventive measure, you’d be way ahead if you get a service crew to clean your gutters and storm drains twice a year (or at least once before the start of monsoon). Your basement floor drains would mostly be connected to the sewer system or in a few cases, to the sump pit. 

To keep the moisture out, you can use membrane sheets and damp proof the ceilings and walls. 

Landscape solutions

Additionally, you can create a swale and rain gardens in the premises and redirect excess water by adding water spouts that flow straight into them and extending downspouts away from the basement into the swale. Extra piping and service may cost some money but works as one of the best solutions for stormwater run-off and flooding prevention.

Raise your vehicles to prevent damages

One practical way of making sure that there’s no real damage to your car is to remove the battery temporarily and jack it up if the flooding is manageable. You can then cover it in a blue tarpaulin sheet so that water doesn’t enter the engine or car flooring. In other preventive measures, you can install ramps in car parking spaces which can be elevated with a flood apex hump at the start of the ramp so that no actual damage occurs to vehicles due to flooding.

Preventive repairs

Make a thorough visual inspection of exterior/interior walls, and the basement ceilings and floors. If there are any cracks, damages, moulds, leaks, corrosion, spalling, foundational damage or distress found, get them repaired before the arrival of monsoon. It’s even better that while you’re getting professional help to make repairs, you have them survey the entire rooftop and property to prevent flooding from any other corner of the building. 

All said and done, there is a possibility that flooding may still occur due to extreme rainfall or other unforeseeable reasons. If there is too much flooding in the basement, do not attempt to remove it manually as there may be toxic pathogens and sewage materials in the water. Instead, call proper civic/waterworks authorities or private contractors to assess and clear the water.

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