Very Small Water System Operator cheat sheet

Coagulation neutralizes particle surface charge so small particles can clump; flocculation gently stirs to build larger, settleable floc.

Sedimentation removes settleable floc; typical design overflow rates for small conventional basins are roughly 0.3–0.8 gpm/ft² depending on solids loading.

Filtration removes residual turbidity and pathogens; a common regulatory limit is filtered water turbidity ≤0.3 NTU in at least 95% of monthly measurements.

Disinfection CT = disinfectant residual concentration (mg/L) × contact time (minutes); required CT rises with pH, temperature, and target pathogen.

Chlorine demand = dose applied minus residual remaining after the contact period; higher demand requires higher dose to hold the same residual.

Free chlorine is more effective than combined chlorine; combined chlorine (chloramines) forms when free chlorine reacts with ammonia-nitrogen.

Turbidity is a key treatment performance indicator: lower turbidity generally correlates with better pathogen removal and fewer disinfection barriers.

Backwash when filter head loss reaches the design limit or effluent turbidity breaks through; typical backwash rates are set by media type and bed expansion.

Maintain a detectable disinfectant residual throughout the distribution system; common targets are 0.2–0.5 mg/L free chlorine at the farthest points.

Pressure must stay positive at all points under normal conditions; a common minimum is about 20 psi to prevent backflow and contamination intrusion.

Water age increases with low demand and dead-end mains; long age depletes residual and raises disinfection by-product formation.

Flushing removes sediment and stale water; unidirectional flushing uses higher velocity in one direction to scour mains.

Cross-connection control relies on air gaps (best) and reduced-pressure-zone backflow assemblies; test annually and maintain records.

Water hammer is a pressure surge from rapid valve closure or pump changes; mitigate with slow-closing valves, surge tanks, or air chambers.

Storage tanks need periodic inspection and turnover; stratification and long storage time can degrade residual and promote biological growth.

Leak detection includes metered night flow, acoustic listening, and step testing; unexplained flow increases often signal main breaks or leaks.

Small systems often serve fewer than 500 connections; operators frequently cover treatment, distribution, sampling, and recordkeeping duties.

Maintain daily logs of chemical doses, residuals, pressures, flows, and maintenance; consistent records are the primary compliance evidence.

Chemical feed pumps must be calibrated; verify dose by measuring drawdown volume over time and cross-check against flow.

Keep a spare parts inventory for critical items such as feed pump diaphragms, chlorine test reagents, and valve seals.

Sample at approved sites and use proper containers, holding times, and preservation; sample handling errors can invalidate results.

Develop a written emergency response plan covering loss of power, loss of pressure, source contamination, and boil water notices.

Operator certification and continuing education are required in most states; track renewal dates and contact hours.

Seasonal risks include source water turbidity spikes after storms, freezing lines, and low-demand stagnation during vacations.

The Safe Drinking Water Act authorizes EPA to set national drinking water standards; states typically have primary enforcement authority.

National Primary Drinking Water Regulations set enforceable maximum contaminant levels (MCLs) and treatment techniques for health-related contaminants.

National Secondary Drinking Water Regulations are non-enforceable guidelines for aesthetics such as color, odor, and corrosivity.

Total coliform rule requires routine sampling; any positive total coliform triggers repeat sampling and evaluation for fecal contamination.

Lead and copper rule uses action levels (0.015 mg/L lead, 1.3 mg/L copper) based on 90th percentile tap samples.

Consumer Confidence Report (annual water quality report) must be delivered to customers by July 1 each year.

Public notification is required within 24 hours for acute violations (e.g., E. coli MCL) and within 30 days for most non-acute violations.

Disinfection by-products are regulated as running annual averages; TTHM MCL is 0.080 mg/L and HAA5 MCL is 0.060 mg/L.