CA Water Operator cheat sheet

Surface water quality varies with runoff, temperature, and watershed land use; turbidity and pathogen risk often rise sharply during storms.

Groundwater is generally more stable in quality but can contain nitrate, arsenic, radionuclides, or salt from intrusion and must be monitored at the wellhead.

Turbidity is measured in nephelometric turbidity units (NTU) and indicates light scattering by particles; it is not a direct pathogen measurement.

TOC (total organic carbon) is a key DBP precursor: higher TOC generally increases THM and HAA formation potential when chlorine is used.

Alkalinity, reported as mg/L CaCO3, buffers pH; low-alkalinity water is more vulnerable to pH swings during coagulation and corrosion control.

The pH scale runs 0–14; values below 7 are acidic and often corrosive, while values above 7 are basic and can promote scaling.

The Surface Water Treatment Rule requires filtration and disinfection for most surface water sources; groundwater under direct influence may be regulated as surface water.

Source water protection uses watershed surveys, wellhead protection areas, and contaminant source inventories to reduce treatment burden and risk.

Coagulation destabilizes particle and NOM charges; common coagulants include alum, ferric chloride, ferric sulfate, and polyaluminum chloride.

Rapid mix disperses coagulant in seconds with high-intensity mixing; flocculation uses gentle mixing for minutes to grow flocs without shearing them.

Jar tests compare coagulant doses and pH values; select the lowest dose that gives clear settled water, good floc, and acceptable filter run length.

Sedimentation removes settleable flocs; performance depends on surface loading rate, detention time, flow distribution, and floc density and size.

Surface loading rate = flow ÷ clarifier surface area; lower loading rates generally improve settling and effluent clarity.

Granular filters remove particles by straining, interception, sedimentation, and adsorption; backwash on head loss, turbidity breakthrough, or run time.

Filter loading rate = flow ÷ filter area; exceeding design rate can shorten runs, increase turbidity, and push particles through the media.

Chemical feed: lb/day = mg/L × MGD × 8.34; dose (mg/L) = lb/day ÷ (MGD × 8.34).

CT = disinfectant concentration (mg/L) × effective contact time (min); use T10 and adjust for pH, temperature, and baffling.

Chlorine demand = applied dose − residual after contact; demand comes from organics, ammonia, metals, and other reducing agents.

Free chlorine reacts with ammonia to form chloramines; monochloramine persists longer but is a weaker disinfectant and can nitrify.

THMs and HAAs form when chlorine reacts with natural organic matter; control by TOC removal, enhanced coagulation, pH control, or alternative disinfectants.

Ozone is a strong disinfectant and oxidant but can form bromate when bromide is present; it provides no distribution residual.

UV disinfection damages nucleic acids and is effective against Cryptosporidium; it requires low turbidity and provides no residual.

Maintain disinfectant residual through distribution; residual loss can indicate nitrification, contamination, or excessive water age.

DPD testing measures free and total chlorine; total chlorine minus free chlorine estimates combined chlorine.

Air gap = highest backflow protection; testable assemblies include RPZ (high hazard), DCVA, and PVB; selection depends on hazard and local code.

Backflow occurs by backsiphonage (negative supply pressure) or backpressure (downstream pressure higher than supply).

Cross-connection control uses containment at the service line and isolation at fixtures; assemblies require annual testing and records.

Unidirectional flushing uses sequenced valves to achieve high velocity in one direction and remove sediment and biofilm.

Water age increases in oversized storage and low-demand areas; high age lowers residual and raises DBP and nitrification risk.

Chloraminated systems monitor free ammonia, nitrite, and residual; a free ammonia rise can signal nitrification.

Storage tanks need turnover, inspection, vent screening, overflow protection, and protection from intrusion; poor tank condition can degrade water quality.

Water hammer is a pressure surge from rapid flow change; air valves, surge tanks, and slow valve operation reduce surge damage.

Total dynamic head (TDH) = elevation head + pressure head + velocity head + friction losses; the pump must overcome TDH at design flow.

Water horsepower = (gpm × TDH ft) ÷ 3960; brake horsepower = water horsepower ÷ pump efficiency.

1 psi = 2.31 ft of water; 1 ft of water = 0.433 psi.

Affinity laws at constant impeller diameter: flow ∝ speed, head ∝ speed², power ∝ speed³.

Cavitation occurs when NPSH available is less than NPSH required; symptoms include noise, vibration, and impeller pitting.

Centrifugal pump operating point is where the pump curve intersects the system curve; throttling changes the system curve and flow.

Positive displacement pumps deliver nearly constant flow against varying pressure and require a relief valve for protection.

4–20 mA transmitter: 4 mA = 0%, 20 mA = 100%; calibrate zero and span and verify loop power and grounding.

SDWA sets national drinking water rules; in California, the State Water Resources Control Board, Division of Drinking Water, enforces primacy requirements.

Nitrate MCL = 10 mg/L as N; arsenic MCL = 10 µg/L; lead action level = 0.015 mg/L and copper action level = 1.3 mg/L.

Stage 2 DBPR MCLs: TTHM = 0.080 mg/L LRAA; HAA5 = 0.060 mg/L LRAA.

Total coliform positives require repeats within 24 hours; E. coli-positive results trigger additional repeat, assessment, and public notification requirements.

Consumer Confidence Report must be delivered to customers by July 1 each year and summarize detected contaminants and regulated limits.

Public notification has three tiers; Tier 1 is immediate for acute health risks, Tier 2 within 30 days, Tier 3 within one year.

Sample integrity requires proper containers, preservation, hold times, and chain-of-custody records; deviations can invalidate results.

Permit-required confined space entry needs atmospheric testing, ventilation, attendant, retrieval system, and trained rescue; LOTO controls hazardous energy.

Chlorine gas is heavier than air and hazardous; use gas detection and respiratory protection, and never use oil on chlorine equipment.