Did you know that 9,400 gallons of water falls onto your roof every year in San Marcos? And even more in some areas of San Diego County. Are your gutters up to the task of protecting your home from that much water flooding?

Do you know how much water flows through your rain gutters each year?

The annual average precipitation in San Marcos, CA is 15.10 Inches. Rainfall is fairly evenly distributed throughout the winter. However the wettest month of the year is January with an average rainfall of 3.37 inches. Source: https://www.idcide.com/weather/ca/san-marcos.htm

An average size house has a 1000 square foot roof. So that means 1″ of rain onto an average roof accounts for 623 gallons of water flowing into the gutters and downspouts.

In January alone there’s nearly 2,100 gallons hitting your roof over the month. These stats for San Marcos are similar for other cities all over San Diego County.

Over the entire year, 15.10 inches of rain is a grand total of 9,407 gallons of water coming off your roof every the year!

So where does all the water go?

If your roof empties into 4 downspouts then each one (in January) is sending 525 gallons of water right to the foundation. If your house has no gutters then all that 2,000+ gallons of water is falling evenly around the perimeter of your house, right next to your walls!

Visualizing 2,100 gallons of Water

  • The average lawn and garden trash can is about 30 gallons. So it takes 70 cans to hold 2,100 gallons of water.
  • A regular size bathtub holds about 40 gallons. So that’s like 53 bathtubs full of water on your roof.
  • An average backyard swimming pool that is 12”x22” holds 9,700 gallons. (Length x width x depth x 7.5 = volume in gallons). That’s like an entire swimming pool of water falling onto your roof over the course of the year!

During a heavy rain the amount of water coming from the downspout is about the same as a bathtub filling at full blast. From what I’ve seen on homes, typically over 70% of gutters and downspouts are clogged (either partially or completely) with leaves, roof dirt, and other debris.

Leaky gutters needed cleaning and repairs.
Leaky gutters need cleaning and repairs.

This is bad because water running down your roof can’t travel through the gutters then down through the downspout. So then it backs up, spills over the sides of the gutters and falls right next to your foundation.

Standing Water Near Your Foundation is Bad

It causes the soil under your home to erode and then that leads to cracks in your slab. It also causes flooding if it gets inside your home. Then that goes up the walls too. So much damage!

But it doesn’t need to be difficult. By properly routing water from the downspouts away from your home you can avoid most if not all of the potential damages.

In San Diego county most of our ground soil is like clay. So making sure that it gets water but not too much is important. That’s because during the summer the clay dries out causing it to shrink and crack. Ground that is shrinking and cracking is unstable. So then the weight of the house causes movement over the changing soil. This is not a good thing!

Likewise, too much ground water causes expansion and loose mud; which then in turn also causes foundation movement. While it’s hard to say which is worse it’s my opinion the too much water is way worse than too little.

So it’s no wonder why so many foundation walls are sinking, cracking and bowing.

Let’s fix it so you won’t have to look up when it rains.

That is why controlling water from gutter downspouts is so important. So call us today for a rain gutter inspection and evaluation. We check to see if your gutter system is in good working order. And if it’s not, then we’ll advise your best course of action for protecting your home.


Owner: Greg Martin
Location: San Marcos, CA. 92069
Phone: 760-445-8762
E-mail: gregmartininca@yahoo.com

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