Residential Water Quality Testing Flashcards
7 cards from real CWS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Residential Water Quality Testing flashcards as text
Which contaminant is associated with agricultural runoff and is known to cause methemoglobinemia ('blue baby syndrome') in infants?
Answer: Nitrate
Nitrate from fertilizers and animal waste reduces oxygen-carrying capacity in infant blood, causing methemoglobinemia.
A customer's water test shows a chloride concentration of 450 mg/L. Which FIRST step should a CWS specialist take?
Answer: Investigate potential sources such as road salt, seawater intrusion, or brine discharge
Elevated chloride warrants source investigation before treatment selection, as the cause (road salt, saltwater intrusion, industrial discharge) determines the best approach.
What is the significance of testing for total dissolved solids (TDS) in residential water quality assessments?
Answer: TDS provides an overall indication of dissolved inorganic load and general water quality
TDS is a broad indicator of dissolved inorganic matter including salts, metals, and minerals, useful for tracking overall water quality changes.
Which water sample should be collected in a pre-acidified bottle with HNO3 for accurate results?
Answer: Dissolved metals sample
Dissolved metals samples are preserved with nitric acid (HNO3) to prevent adsorption onto bottle walls and to keep metals in solution.
A water softener regenerates with salt brine and discharges to a septic system. Which water quality parameter might increase in the household well over time?
Answer: Sodium and chloride
Softener regeneration brine adds sodium and chloride to septic effluent, which can leach back into shallow groundwater and increase well water sodium and chloride levels.
Which parameter is used to calculate the Ryznar Stability Index (RSI), an alternative to the Langelier Saturation Index for predicting scale and corrosion?
Answer: pH, pHs (saturation pH), temperature, calcium, alkalinity, and TDS
The RSI uses the same variables as the LSI (pH, pHsat, calcium, alkalinity, TDS, temperature) to predict whether water will be scale-forming or corrosive.
A residential well test detects uranium at 35 µg/L. What is the EPA MCL for uranium in drinking water?
Answer: 30 µg/L
The EPA MCL for uranium in drinking water is 30 µg/L, set to protect against kidney toxicity from chronic exposure.