Category Archives: Regulation

Starting Blocks and Water Depth: Is Your Pool Safe?

When it comes to the world of competitive swimming, there are stringent guidelines that everyone involved in the pool design process must take into consideration. This is especially true for water depths beneath starting blocks.

Starting blocks are raised platforms typically mounted on the pool deck at the end of competitive swimming lanes. In most installations, the height of the starting block platform above the water surface is less than 29 ½” above the water surface. Swimmers mount the blocks and push off from a crouched position, using the force from their lower bodies to launch into the pool. We’ve seen many technological advancements for modern day starting blocks, with the most recent changes being the addition of rear footrests and side handles, which can have an impact on a swimmer’s overall performance.

Because swimmers are diving with a lot of force, it is crucial to ensure that the water beneath the starting blocks, as well as a portion of the pool length ahead of the swimmer, is deep enough that swimmers will not injure themselves. Diving into water that is too shallow can result in devastating injuries.

Credit: Indiana University-Purdue University Indianapolis

If a swimmer hits their head on the bottom of the pool, a massive amount of force is transferred to the spine. This force can sometimes collapse the vertebrae that encircle the spinal cord, potentially leading to paralysis or worse. For this reason, it is important for an appropriate water depth to be maintained at the ends of pools where swimmers are diving into the water. In addition to this safety concern, sufficient water depth beneath a starting block can provide a swimmer with the best opportunity to maximize the performance of their start.

USA Swimming, the national governing body of competitive swimming in the United States, has its own set of racing start standards that vary based on swimmer experience and training. In pools with water depths less than 4’-0” at the starting end, all swimmers, regardless of skill level, must begin from within the water. In these instances, backstroke starting ledges are also not permitted. For pools that have water depths between 4’-0” and 6’-0”, a swimmer can utilize a starting block if they have been certified by a USA Swimming Coach. For water depths greater than 6’-0”, starting blocks are allowed for all swimmers, regardless of skill.

FINA, which serves as the international governing body of competitive swimming, has its own standards. The minimum depth at the pool’s end has to be 1.35 meters (about 4’-5”). But when it comes to all Olympic and World Championship events, pool depth must remain a minimum of two meters (about 6’-6”) throughout the entire field of play, with three meters (about 10’-0”) preferred.

It’s important to note that various industry organizations and jurisdictional health and safety departments all have their own defined standard, as well as several varieties of the standard based on different factors. For instance, some organizations have a defined range of water depth standards that are dependent upon the pool type or user. Others take it as a case-by-case basis, and vary the depth as appropriate. Additionally, there are local, state and municipal regulations that need to be considered. What is too shallow for one group may be sufficient for another.

At Counsilman-Hunsaker, we make things simple by recommending a minimum water depth requirement of 6’-0” (with 7’-0” preferred), that is to be maintained a minimum of five meters (16’-5”) from the end wall. This is a universal standard for all pools we work on, regardless of pool type or user, that ensures your pool will be competition-ready. These recommended water depths will also allow a swimmer to utilize a starting block with minimal risk to their health and wellbeing.

Swimmer safety is a top priority for Counsilman-Hunsaker. We take time to assess our systems and specifications to ensure we are designing pools that are not only functional and aesthetically-pleasing, but also keep swimmers safe and able to pursue aquatics for life. Be sure to follow us on social media for more aquatic design and operations information!

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What does the ADA require for pool access?

According to the American Disabilities Act (ADA), every pool must have at least two means of ADA access. There are three main means of ADA access that can be considered for pool design:  a fixed pool lift, ramp entry and stair entry. Counsilman-Hunsaker’s standard approach to meeting ADA guidelines is to design our pools with two means of access.  The first means of access is a fixed pool lift on deck required by the Department of Justice.  With multiple pool lift manufacturers, there are many options available.

Our second option is to use a ramp entry. A ramp entry tends to take up a lot of valuable space in the pool. It requires a one to twelve slope and a five-foot landing zone at either a 24-inch or 30-inch water depth. It will also need to be 38 inches wide from handrail to handrail to allow for a wheelchair to pass through. Depending on the depth of the pool, the ramp could be as long as 47 feet. You can shorten this length by adding a switch back at the 18-inch or 24-inch deep landing zone. By doing this, the total width of the ramp could become 8’-4” or 9’-4” if you add a wing wall to separate the ramp from the rest of the pool. Depending on the venue of the pool being designed, a ramp entry might be a must, especially in therapeutic or rehabilitation centers, where most of the users will be in a wheelchair.handicap lift

On the other hand, an ADA stair entry, which is our third option, takes literally no space at all if the pool is already designed with stairs. To make them ADA-compliant, an additional handrail would be added to the stairs 24 inches off of one of the side handrails. Other than the pool lift, this is the easiest option to comply with the ADA since most pool are designed with a stair entry. Cost-wise, it is a lot less expensive to construct a stair entry than it is to construct a ramp entry.

With the options that we have available to meet the ADA requirements, Counsilman Hunsaker’s typical approach is the option of one lift and an ADA stair entry to meet the requirements. If we are designing a pool for a venue that is for rehabilitation or therapeutic uses, we would design the pool with a pool lift and an ADA ramp entry. By adding in a stair entry with ADA-spaced hand rails, we have covered all three means of access.


Diving – Top 10 attributes of a world-class venue

The design of a world-class diving venue requires understanding diving facility guidelines, diving competition rules, and the intricate interactions between divers and their environment.

First and foremost, a dive facility must meet the minimum standards of the competition taking place. For example, the overhead clearance above the diving boards and platforms must be at least that specified in the NFHS, NCAA, USA Swimming & Diving, and FINA diving regulations. This is typically five meters (16 feet, 5 inches) above the highest diving board or platform and is in place so that divers do not hit the ceiling structure. This is just one of numerous design considerations for an elite diving venue.

So, what additional attributes make a world-class diving facility? Here’s a top-10 list:

  1. SEPARATE DIVE POOL – This allows for swimming and diving training to take place simultaneously, as well as accommodate world-class diving events.
  2. 10-METER PLATFORM TOWER AND SPRINGBOARDS –Platform diving competition takes place at 10 meters, though 1-, 3-, 5-, and 7.5-meter heights are also typically provided for training and warm-ups.
  3. DARK-COLORED BOTTOM – It is recommended by USA Diving that the bottom of the dive pool be a dark color — typically dark blue or black — and the walls white.
  4. SPARGERS AND WATER-SURFACE AGITATORS – Spargers (air-bubbling systems) are utilized for diving practice. Water-surface agitators are used during competition to break up the reflection of the ceiling or sky.
  5. SPA AND/OR SHOWERS – A desired feature at all major diving facilities, a spa allows divers to relax their muscles before or after dives.
  6. LARGE STAIR SYSTEM – All world-class diving pools have a large stair system for easy egress out of the pool after a dive.
  7. DIVING HARNESS/SPOTTING RIG – In elite facilities, there may be two diving harnesses and spotting rigs — mounted over one springboard and one platform.
  8. DRY-LAND TRAINING ROOM – For high-level diving, a separate dry-land training room should be provided and equipped with dry-land springboards and pits, a trampoline and digital video recording capability.
  9. SPECTATOR SEATING AND JUDGE VIEWING – Some meets are held using only temporary seating, while large world-class diving events have recently been staged with temporary pools in front of 10,000 or more seats.
  10. LIGHTING AND TV CONSIDERATIONS – During major competitions, lighting levels should be close to 200 foot-candles. Practice lighting can be less, but still needs to be in the 75-to-100-foot-candle range.

Examples of World-Class Diving Venues

The following examples show three world-class diving venues. The University of Tennessee is an indoor facility. The St. Peters Rec-Plex is also an indoor facility, but a municipal diving center. Stanford University is an outdoor diving venue.

The University of Tennessee’s Allan Jones Intercollegiate Aquatic Center isTennessee, Univ of (1) a complex capable of hosting NCAA Championships, the Southeastern Conference, and national and international events. The center offers seating for 1,800 spectators with a spacious deck area to comfortably accommodate up to 2,000 additional individuals during meets. This 72,000 sq. ft. state-of-the art swimming and diving facility is highlighted by an eight lane 50-meter by 25-yard competition pool and a separate diving pool with 1, 3, 5, 7½, and 10-meter platform diving.

The City of St. Peters, Missouri, Rec-Plex is IMG_6008a world-class aquatic complex constructed for its nationally recognized aquatics program and to host special aquatic events. The Rec-Plex hosted the Olympic Festival in 1994 and the Olympic Diving Trials in 2004. This state-of-the-art natatorium includes a diving tower with 1, 3, 5, 7½, and 10-meter platform diving and a whirlpool spa.

As one of the most prestigious universities in the nation, Stanford University is not only recognized for academic excellence but also outstanding programs in athletics and aquatics. Since 1920, the university has collected countless national awards and trophieProfessional Diving tower nights, turning out some of history’s finest Olympic aquatic athletes. In 2001, Stanford built a world-class venue for the school’s highly-acclaimed aquatics program. The high-tech facility consists of four separate outdoor pools including:

  • 8,200 sq. ft. stretch 25-meter competition pool with diving boards and bulkhead
  • 13,850 sq. ft. 50-meter by 25-meter by 3-meter training pool with bulkhead
  • 4,600 sq. ft. diving pool with a 3-centerline tower and four springboards
  • 50-meter recreation pool
  • Two whirlpool spas (72 sq. ft. and 130.5 sq. ft.)

Chemical Treatment Options For Commercial Pools

All public swimming pools require sanitizing systems to eliminate microbes in the water to provide a healthy swimming environment.  There are many options available today and there are some common misconceptions regarding what systems are available and their relative merits.  The purpose of this overview is to provide some basic information about these systems and their effectiveness, safety, and practical application.

There are three basic categories of water treatment systems commonly used in swimming pools: Sanitizers, Supplemental Sanitizers, and pH Buffers.


All public swimming pools must have a chemical sanitizer, as mandated by the local public health code. The function of the sanitizer is to kill micro-organisms.  This is generally done by adding a chemical sanitizer to the water as it passes through the treatment system in the pool equipment room.  This effectively treats the water at the point of injection, but also leaves residual sanitizer in the pool water itself to handle contamination sources in the pool.  The following options are available:imagesCAH3FQ1H

  1. Sodium Hypochlorite
    1. 12% free available chlorine
    2. Liquid
    3. Dilutes over time
    4. Classified as an irritant
  2. Calcium Hypochlorite
    1. 65% free available chlorine
    2. Tablet
    3. Longer shelf life than sodium hypochlorite
    4. Classified as a Class 3 oxidizer and is corrosive
  3. Gas Chlorine
    1. 100% free available chlorine
    2. Gas
    3. Chlorine gas is extremely corrosive and has been known to corrode all metal within an equipment room.
    4. Not allowed by most health codes due to hazardous nature.
  4. Bromine
    1. Commonly used on smaller bodies of water (hot tubs) with low bather loads.
    2. Twice the bromine is required to reach the same oxidation potential of chlorine.
    3. Bromine is a much less aggressive oxidizer compared to chlorine.
    4. Bromine BCDMH is classified as a corrosive – either class one or class two oxidizer. It is not flammable in and of itself, but it may ignite combustible materials in which it comes into contact, and as such is identified as a hazard.
  5. Chlorine Generation (Salt System)
    1. Non-ionized, coarse, sun-dried or pelletized salt (normally in 40 lb. bags) is initially added to the pool water to develop a concentration of 0.5% (5,000 ppm).
    2. A small amount of electricity is used by the chlorine generator during the electrolytic process.
    3. Salt systems generate pure sodium hypochlorite at a near neutral pH and therefore have less effect on pH than most other pool chlorines.
    4. 4 ppm of free chlorine is reported to be ten times more corrosive than 4,000 ppm in salinity.


A common misconception is that salt systems provide a chlorine-free pool.  This is incorrect.  Chlorine serves as the primary chemical sanitizer in all of the above systems except Bromine.


In addition to the above chemical sanitizers, secondary water treatment systems are available to further improve the water quality.  It should be noted that none of these systems are permitted by health codes to serve as a primary source of water treatment.  They are only permitted as supplementary systems.  This is because they do not result in providing any residual chlorine in the pool itself, where contamination is most likely to occur.  Water is only treated in the equipment room.

However, the advantage of these supplemental systems is in their effectiveness at reducing Chloramines (combined chlorine).  Chloramines  are compounds formed when chlorine combines with other chemicals from human perspiration, body oils, and other byproducts.  These chloramines have been shown to affect the air quality in the natatorium, particularly just above the surface of the water.  It is the “chloramines’ in the air which produce the common “chlorine smell” often experienced at indoor aquatic facilities if not treated effectively.  They have been shown to cause health problems, particularly in people with respiratory problems such as asthma.  These supplemental sanitizers are also effective as sanitizers, even though not permitted as a primary means.  These systems include:

  1. Ultraviolet Light (UV)
    1. Reduces combined chlorine (chloramines). Indoor air quality will improve.
    2. The frequency of super-chlorination of the pool is reduced with UV installed.
    3. UV is highly effective against chlorine resistant pathogens like Cryptosporidium and Giardia; as well as the vast majority of bacteria, viruses, yeast, and mold.

i.      Chloramines reduction: < 0.2ppm

ii.      Disinfection: > 99.99% for Cryptosporidium and E. coli.

  1. Medium pressure.
  2. Need to budget $1,000 per year for bulb replacement.
  3. Ozone
    1. Reduces combined chlorine (chloramines). Indoor air quality will improve.
    2. The frequency of super-chlorination of the pool is reduced.
    3. Full DIN system treats 100% of flow – very expensive
    4. Sidestream Ozone system treats approximately 25% of flow – still very expensive.
    5. Ozone systems are very complicated to operate – need pool operator that has experience with Ozone.


The sanitizers discussed in this overview have a high pH and thus raise the pH of the pool water therefore it is necessary to add pH buffers to lower the pH levels of the pool.  The options available are:

  1. CO2
    1. CO2 (Carbon Dioxide) is a pH balancing chemical that is effective with “soft” source water.
    2. Used when the total alkalinity is less than 70 ppm. CO2 raises the TA in the water.
    3. CO2 is injected into water to release oxygen and carbonic acid.
    4. No fire rating is required.
  2. Muriatic Acid
    1. 31.5% solution of hydrochloric acid.
    2. Muriatic acid reacts with the sanitizer, thus counteracting the pH, raising effects of the sanitizer. It has a pH of approximately 3. In the pool, it will lower the pH and total alkalinity. Typically delivered in 15-gallon carboys.
    3. Muriatic acid (hydrochloric acid) is classified as a corrosive and is highly reactive.
    4. Muriatic acid is used where the total alkalinity in the source water is above 70 ppm.

Bather Loads

Understanding bather load requirements in a swimming pool environment is all too often overlooked when designing an aquatic facility.  While design considerations for an aquatic facility are commonly related to architectural and engineering aspects, allowable bather loads can also have long term impacts to your facility operations.

Bather load requirements generally vary amongst state swimming pool facility codes.  Traditional approaches have focused on the premise that 468-crowdedpoolmore swimmers will commonly be gathered within shallow water areas, as compared to deeper water areas.  As a result, these customary design requirements use water surface area as the primary factor when determining bather load.  Allowable load factors will vary based upon the water depths, with shallow water areas (less than 5’-0”) and deep water areas (greater than 5’-0”) separated into different categories.  Many standards use 15 square feet per bather for water areas less than 5’-0” and 25 square feet per bather for deep water areas.  Additional considerations are also given to the inclusion of water activities such as diving boards and water slides, where dedicated water area for each of these activities is subtracted from the overall water surface area.  For example, many codes require 300 square feet of water surface area for each diving board, which will be deducted from the overall deep water area when calculating bather loads.  In addition to the bather load allowances for shallow and deep water areas, some state swimming pool codes will include additional bathers in the facility based upon the amount of deck area that is provided.  The reasoning with this additional bather allowance is there will likely be people who spend a portion of their time not in the water.  An allowance for additional bathers as a result of pool deck might be 1 bather for every 50 square feet of excess pool deck.  Excess pool deck is typically defined as all deck areas that are beyond the minimum requirements, which is commonly established at 4’-0” to 5’-0” from the pool edge.  Additionally, the Model Aquatic Health Code (MAHC) also stipulates that deck areas beyond twice the amount of water surface area is treated differently than deck equal to or less than the water surface area.

While the aforementioned approach has been widely accepted in the swimming pool industry for many decades, the MAHC has considered a more scientific methodology to bather load calculations.  The MAHC utilizes a Theoretical Peak Occupancy (TPO) as a means approach when assigning the maximum number of allowable occupants or users at an aquatic facility.  The significant difference in the MAHC approach is the TPO calculations are based around the type of water in lieu of the water depths.  The following water areas definitions can be found within the MAHC:

  • Flat Water means an aquatic venue in which the water line is static except for movement made by users usually as a horizontal use as in swimming. Diving spargers do not void the flat water definition.
  • Agitated Water means an aquatic venue with mechanical means (aquatic features) to discharge, spray, or move the water’s surface above and/or below the static water line of the aquatic venue so people are standing or playing vertically. Where there is no static water line, movement shall be considered above the deck plane.
  • Hot Water means an aquatic venue with a water temperature over 90oF (32oC).
  • Stadium Seating means an area of high-occupancy seating provided above the pool level for observation.
  • Specific Use Area mean water areas that are dedicated for a very specific use such as waterslide landing pool areas and interactive water play areas.

For each of the aforementioned areas the TPO is calculated by dividing the water surface area in square feet by the density factor (D).  Density factors for water areas range from 20 SF per bather for flat water, 15 SF for agitated water, 10 SF for hot water and interactive play areas.  For non-water related spaces density factors area considered such as 50 SF per bather for pool deck and 6.6 SF per bather for stadium seating.  The overall TPO is then determined by adding the calculations for each aquatic venue within the aquatic facility.  The scientific theory behind using the TPO approach is that the number of users should be based upon the impact from various water spaces and the anticipated users within these spaces.  In addition to bather load, design parameters such as natatorium air handling systems are impacted by the TPO.

Ultimately, the determination of bather loads or theoretical pool occupancy will impact not only how many patrons will be allowed to use an aquatic facility, but significant design considerations must be given to locker room and restroom hygiene fixtures.  Quantifying toilets, urinals and other hygiene fixtures, excluding showers, shall be based upon the greater of current applicable jurisdictional codes, or the MAHC calculated maximum theoretical peak occupancy. Lastly, consideration should always be given to what meets code requirements and what actually seems and feels reasonable.  Whether bather load determinations are based upon water areas as segregated by depth or type of water, one must consider the reality of the bather load numbers, and use practical and common sense when assigning final loads.  While exceeding code allotments may not be possible and certainly not recommended, a reduction in the allowable bather loads may be considered.  This reduction in allowable theoretical peak occupancy may provide not only a relief from excessive hygiene fixture requirements, but may result in a better user experience.