A municipal well is a forty-year asset built in a few weeks, and almost everything about how it will age is decided in those weeks. Districts that own the construction record — not the invoice, the record — can anticipate plugging before it costs them, trace sanding back to a screen and slot size on file, and specify the next well from evidence rather than memory. This is what that record should contain and why each item matters.
Casing
Casing diameter sets the largest pump the well can ever take and the column losses it will carry; material sets its corrosion life. Low-carbon steel is standard for large municipal wells, with heavier wall where the water is aggressive; stainless steel or copper-bearing steel where corrosion is expected; PVC for smaller, shallower wells. Record the diameter, wall thickness, material and joint type by depth interval — a well with a reduced-diameter liner installed later needs both.
Screen
The screen is where the well meets the aquifer and where plugging happens. Three families are common in California municipal wells: louvered (shutter) screen, bridge-slot screen, and continuous-slot wire-wrapped screen, which offers the most open area for a given slot. Slot size is selected from the sieve analysis of the formation (or of the filter pack) so that the pack is retained and the formation is developed. Record the type, material, slot size and every screened interval — the perforated intervals are what the GSA’s monitoring-network form and every future video survey refer to.
Filter pack
The gravel (filter) pack is sized from the formation’s grain-size distribution — a pack-to-aquifer ratio in the mid single digits against the formation’s finer fractions is the classic rule — and it must be clean, well-rounded and placed without bridging. An under-sized pack or an over-sized slot is the usual origin of a well that pumps sand for life; an over-sized pack plugs early with fines. Keep the sieve analyses, the pack gradation and the volume placed.
Seal and sanitary construction
The annular seal keeps surface water and shallow poor-quality water out of the well and the aquifer. The California Well Standards (DWR Bulletins 74-81 and 74-90) set minimum seal depths, and local ordinances often go deeper; community water-supply wells are commonly sealed to at least 50 feet. The Division of Drinking Water will ask for the seal depth and material when the source is permitted and whenever it is modified.
Development and the baseline test
Development — surging, airlifting, jetting, over-pumping — removes drilling fluids and fines and settles the pack; skipping it leaves a well that never reaches its potential and sands for years. The development log, followed by a step-drawdown test and a constant-rate test, gives the well its baseline: the specific capacity and the well-loss coefficient every later test is compared against. Without that baseline, the question ‘has this well plugged?’ has no answer.
The documents to keep
- The DWR well completion report (driller’s log) with the lithologic log
- Geophysical (electric) logs and the sieve analyses
- The casing and screen schedule and the filter pack record
- The development log and the step and constant-rate test reports
- The initial video survey, and every later one
- The pump installation record: model, stages, setting depth, motor nameplate
Waterwell IQ™ stores all of these against the well, reads the driller’s log and test reports with AI so the perforated intervals and baseline numbers become data rather than scans, and draws the well as built in the well cross-section. The contractor account lets the driller file the record directly at completion.
See a well’s construction record read from its own driller’s log. Request a walkthrough →
Sources
- U.S. Geological Survey. Filter-Pack and Well-Screen Design, Open-File Report 63-60, A. I. Johnson. 1963. The classic reference for slot size and filter-pack gradation ratios; still widely cited, and old enough that current state standards govern where the two differ.
- California Department of Water Resources. Water Well Standards: State of California, Bulletin 74-81. 1981.
- California Department of Water Resources. California Well Standards: Water Wells, Monitoring Wells, Cathodic Protection Wells — Supplement to Bulletin 74-81. January 1990. DWR states the final draft was circulated for comment in November 1989 and the comments incorporated into this bulletin. Check your county ordinance for what it actually adopts; local standards govern.
- American Water Works Association. ANSI/AWWA A100-20, Water Wells. 2020. Paid standard, cited by designation.
Every link above was retrieved and read on 2026-09-09. Paid standards are named by designation so you can check them against your own copy.