Why Basements Don’t Flood: How Sump Pumps Work



Ever wonder how we manage to build basements that don’t constantly flood out if water (almost) always flows to lower ground?

It’s not that they don’t take on water – they do. It’s that they’re designed to push out the water as fast as it comes in.

Enter sump pumps

Sump pumps are specialty pieces of equipment put in place to make sure your basements don’t flood. Water that enters the substructure collects in (sump) pits where its siphoned by the pumps and ejected outside of the building.

They’re designed at a capacity to match the amount of water you’d expect to enter the space. But, with climate change being what it is, recent weather hasn’t been playing by the rules.


Between Ondoy (international name Ketsana,) and the succeeding Habagat rains, pretty much the entirety of Manila was submerged in flood. Even houses LVLP has built in the exclusive enclaves of Makati weren’t spared from having their basements flooded out.


Basement flooding is typically a symptom of one or a combination of the following root problems –

  1. Water comes in faster than it can be pumped out. Rain can drop especially heavy or flood rises high above street level, cascading into your basement. The pump loses by sheer volume and can’t cope with the influx.
  2. It’s been raining for too long and the pump isn’t able to handle the extended use. Depending on the model or supplier, some sump pumps are actually designed to run continuously. Domestic pumps however may only be designed to run up to 5 hours in a day. Longer than that, end they might breakdown, leaving you nothing to keep your basement dry.
  3. There’s nowhere to eject water to. Sump pumps work on the principle that it takes water from the basement and pushes it out somewhere else. This would normally be the storm sewer which which also has a limited capacity,and has a tendency to be clogged with detritus and trash (read- fatburgs [LINK]). With nowhere to eject to – the system chokes and the basement floods.
  4.  Surprise, your sump pump is broken! As with all equipment it’s imperative that your equipment is maintained and is in good working order. Sump pits and pumps tend to accumulate dirt and debris, and its essential that its cleaned regularly. Different types of pumps will also have different life spans. Some domestic models have a lifespan of just 10 years. It will be good to know. Its best that you replace it early, than when it’s too late.

Worry vs Value

There’s nothing like a flooding mansion to make you ask if you should even be designing basements at all. (I mean, if even the most money-backed houses that can afford the necessary equipment suffered the inundation, what more houses of a moderate budget?)

Given the cost of land though, sometimes its something you have to do to get your money’s worth, while also meeting the client’s program. What’s important regardless of budget is that your basement treated right, having learned lessons from the disasters we couldn’t have predicted previously. (Escalating acts-of-god notwithstanding.)



Pumping flood water out aside, its also important that certain design details are kept to make sure you’re minimizing water entry to your substructure in general. If sump pumps are the sailor assigned to bail water out of a filling boat, these mitigating details make sure your vessel is taking on a little water as possible to begin with. We’ll cover these details next week, so be sure to check in again then.


Quick Questions, or have a basement flood story you’d like to share?
Email homebydesignph@outlook.com or leave a comment.

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Jiddu Bulatao

War on Heat 2: Designed to Breathe

10 - WOH2 Designed to Breathe - Cover

(This is the 2nd in a series of articles tackling how we might possibly deal with the indomitable heat in the Philippines. If you haven’t checked it out yet, visit War on Heat 1: The Cover Up. It might just save your life.)

Even if you were able to insulate your home 100%, it doesn’t mean it’ll be heat free. Try as hard as you might to keep it out, there will always be heat indoors. Your dog, the equipment you might have running, the sexual tension between you and the person beside you – all of these generate heat without having anything to do with the sun. At night the situation is even worse. As covered in part 1, your concrete hollow block walls re-radiate the heat into your space. Your enemy is already inside. You need a way to get that hot air out.

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War on Heat 1: The Cover Up

09 - WOH1 The Cover Up
War on Heat 1:  The Cover Up.


Just kidding, this is the Philippines. Even through the coldest months of December to February, heat is still one of the biggest issues to issues to handle in a Filipino house.

(This is the first of 3 articles on the War on Heat. So check in soon, and see if you can’t find anything that can help you against this godawful heat.)

It’s the age old problem. Even the OG bahay kubo and the bahay na bato were developed to combat heat and humidity. It might have been a completely different era, but techniques and components like long overhangs, and permeable materials and screens were developed to keep the heat out and let the home breathe. Today, these principles still hold true as methods of keeping a home cool and comfortable.

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