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Pools, Spas, and Water Features – What You Should Know

August 2022. We are well into summer swim season and under current water restrictions there are a few considerations regarding swimming pools and spas that residents should keep in mind.

Pool cover (1)

Keep it Covered

Outdoor pools and spas must be covered when not in use. Why? Uncovered pools use as much water (losing it through evaporation) as lawns. Pool covers reduce evaporation by more than 50% so cover your pool and/or spa whenever it is not in use. Does this mean you have to cover it each time you get in and out of the pool to use the restroom or make lunch? No, but if you plan on being away for an extended period (say, two hours or more) please cover it until your next use. Most importantly, keep it covered at night, while on vacation, and when no one is using it. Added bonus: you will save money on both water costs and heating the pool as the cover will retain the pool’s heat.

What kind of pool cover?

There are three types of pool covers: 1) vinyl “bubble” cover, 2) retractable heavy-duty vinyl cover, 3) chemical or liquid pool cover.

  1. Vinyl “bubble” cover – the most affordable cover; can be custom cut to any pool shape. The pool cover does not have to be one continuous piece. Your pool can be covered with multiple smaller pieces providing coverage for most of the pool. Vinyl bubble covers can be purchased by the yard at most pool supply stores and online retailers, and cut with a pair of scissors.
  2. Retractable – this type makes it easier to cover your pool, either by hand crank or electric/motorized means, but retractable covers are costly and installation is more complex. They are also rectangular in shape so best utilized on rectangular shaped pools.
  3. Chemical – a convenient option is a “chemical” or “liquid” pool cover, which is not a blanket but a liquid – a mix of alcohol and calcium hydroxide that is lighter than water and floats on its surface, creating a film-like barrier that you can’t see or feel. This invisible layer holds in heat and reduces evaporation. The chemical is not permanent and will need to be re-applied on a weekly or more frequent basis, depending on pool use. This type of cover is not as effective at reducing evaporation but can be utilized when the physical blanket options are not practical.

Pool and Spa Filling

Under the City’s current (Level 4) water restrictions, draining, re-filling, and topping off pools and spas with more than one foot of potable water is prohibited. If draining and re-filling is necessary to fix a leak or address an emergency repair you must request an exemption by emailing with your name, address, and phone number, and include documentation from a licensed pool contractor or leak detection service (a proposal/bid/contract/invoice) clearly stating that a leak has been identified in the pool shell, and in order to repair the leak and prevent further water loss, the pool must be drained, repaired, and refilled. You are not permitted to drain and refill your pool for cosmetic purposes, re-plastering, filtration, cleaning or chemical treatment. If your pool is properly maintained, it should require draining no more than once every 5 to 10 years.

Pool/Spa Draining

If you receive authorization to drain and refill your pool due to a repair, there are specific procedures to consider.

  1. Chlorinated Pools/Spas:

    The City of Thousand Oaks does not require a permit to drain a pool/spa, but the pool/spa owner must use the following methods to dispose of the water.

    For discharge into the sewer system:

    Pump water into a sewer cleanout or other sewer connection located on the property while carefully monitoring the flow to avoid flooding.

    For discharge into the storm drain system:

  • Reduce the chlorine level to a maximum of 0.1 ppm (parts per million) using a dechlorinator filter as necessary and treat water to obtain a pH reading between 6 and 8 prior to draining.
  • Ensure water is clean of algae, debris, and mosquitoes before draining.
  • Make certain that the water draining from your pool will not push over trash carts, flood streets, or pick up dirt, lawn clippings, leaves or other debris as it makes its way to the storm drain.
  1. Saltwater Pools & Spas

    It is illegal to discharge the water from saltwater pools and spas into the sewer or stormwater system. Please read important notice about Saltwater Swimming Pools and Spas.

  • Water from saltwater pools and spas must be hauled for disposal via truck to a proper ocean discharging disposal facility.
  1. Proper Disposal of Pool Filter Backwash/Cleaning:
  • Never dispose of filter material (i.e. diatomaceous earth (DE)) in the street, gutter or storm drain system.
  • DE filter waste should be bagged wet and disposed of in the trash.
  • If DE filter requires rinsing, it should be rinsed to a landscaped area on the pool/spa owner’s property through a filter bag to catch sediment and then dispose of the bag in the trash.

Ornamental lakes, ponds, and running water features

Topping off, filling or re-filling ornamental lakes, ponds, or running water features with potable water is prohibited, except to sustain aquatic life of significant value.

My fountain uses recirculated water. Do I need to turn it off?

Yes. Even if your fountain recirculates its water, there will be loss from evaporation. That water loss is refilled from the potable water supply. The only exception is where there is valuable aquatic life reliant on the water feature for survival (e.g., Koi).

Can I fill a kiddie pool?

Yes. You must not fill with more than one foot of water and please drain on to landscape when finished.

What happens if I ignore the pool requirements?

The three local water providers are actively monitoring and enforcing water restrictions. If it is reported that a resident is non-compliant with pool requirements, they could receive a violation notice and potentially a fine. Does this mean that enforcement staff will be entering backyards or looking over walls to see if your pool is covered? No, but we are asking that everyone comply in good faith and do their part to conserve so that our community reaches its water use reduction target of 50% and avoid a possible zero outdoor irrigation mandate this Fall.  

Thank you for your cooperation. For more information visit



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