Source Water and Water Quality
What to know
Source water work starts with understanding where the water comes from and what can contaminate it. A candidate should distinguish surface water (rivers, lakes, reservoirs - exposed, variable, biological and turbidity risk) from groundwater (wells, springs - generally more stable, cooler, lower in turbidity, but vulnerable to chemical contaminants and susceptible to surface influence under the direct-influence rule). Know the meaning of turbidity, color, odor, pH, alkalinity, hardness, TDS, and conductivity, and which are aesthetic versus health-related. Understand watershed protection, wellhead protection areas, setback distances, and source water assessment concepts. Know the difference between a primary (health-based) standard and a secondary (aesthetic) standard, and recognize that nitrate and pathogens are the classic groundwater risks while Giardia/Cryptosporidium, algae, and DBP precursors are classic surface-water concerns.
Traps
Questions often swap surface and groundwater characteristics, or imply that a secondary standard is enforceable on health grounds. Watch for confusing turbidity (a treatment/indicator parameter) with TDS (dissolved solids). Another trap: assuming all groundwater is pathogen-free - under the influence of surface water, it is not.
Worked example / rule of thumb
If a well is 30 feet from a septic system and the state setback is 50 feet, the well is non-compliant regardless of water quality results - setbacks are preventive, not performance-based. Rule of thumb: surface water = variable quality needing full treatment; groundwater = stable quality but verify source protection.
Study tip
Map each source type to its top three contaminants and the treatment that addresses them.