17537 132nd Ave NE Woodinville, WA 98072 (425) 487-6400 info@kriscopools.com

The Seattle area is a wonderful place to invest in a swimming pool. Our hot summer days provide plenty of opportunity to indulge in a quick dip. Temperatures in the winter rarely dip below freezing for long, which means you rarely have to worry about your pool’s condition after a hard freeze.

Seattle’s nearly 150 days of precipitation provide nearly 38 inches of water each year, which can present challenges for pool owners. Fortunately, you can overcome these challenges with some basic pool maintenance.

Does Rain Affect Your Pool Water?

Technically, all those millions of water droplets don’t cause harm to your pool water. However, what’s contained inside each raindrop does make an impact.


In order for a drop of rain to form from the moisture inside a cloud and fall to earth, it must cling to a tiny bit of dust or other matter. This means each raindrop can contain algae spores, pollen, and dirt. In addition, rain sweeps additional debris present in the air and into your pool. Worse, rainwater washes from the ground or pool deck and into your water.

One popular myth is that rain dilutes the chemicals in your pool water, weakening its potency. This is not necessarily true, however.

A small 10X20 pool with an average depth of 5 feet holds nearly 7,500 gallons of water. One inch of rain only adds 125 gallons of water, increasing the pool’s volume by a mere 1.6% — not enough to affect the chemical composition. Only heavy rain would impact the chemical concentration.

What Can Happen to Your Pool Water?

After heavy rain introduces dirt, spores, and other debris into your pool, alkalinity and pH levels are impacted as total dissolved solids and calcium hardness increases.

Alkaline Levels

Alkalinity refers to how many alkaline materials are present in water, mostly sodium and potassium. A safe level is around 100 ppm. A very high alkalinity will encourage the growth of scale deposits on every surface coming into contact with water, including expensive equipment and plumbing. The pool water will also look cloudy.

Low alkalinity means the water is very acidic and your pool equipment and surfaces begin to corrode.

pH Levels

The term pH refers to how acidic or basic the water in your pool is. When pH levels rise too high, chlorine can no longer perform effectively, forcing you to add more. You will be able to feel a high pH when you swim and your eyes redden and skin feels drier. Even swimwear takes a beating and wears out more quickly.

The effects of a low pool pH are similar to those of high alkalinity. An optimum pH level is between 7.4 and 7.6.

Will Too Much Rain Overflow Your Pool?

You may be worried about your pool overflowing as a winter storm brings many inches in just a few days. Fortunately, skimmers and drains both work to remove any excess water easily.

If a storm brings heavy rain, your pool may be completely full after the storm leaves the area. In this case, simply lower the water level to normal.

For solutions check your pool water frequently or consider a winter pool cover to protect your water. If you are concerned about maintaining healthy water levels in your pool, visit the professionals at KrisCo Aquatech Pools & Spas.

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