Korea-specific calculator · current law checked August 21, 2026
Compare complete life-cycle costs, not a drilling quote with a water bill
A groundwater well can look inexpensive when only the drilling line is compared with municipal water charges.
A decision-grade comparison also needs investigation and design, mobilisation, casing and grouting, pumping equipment, electrical work, treatment, reinstatement, failed-hole risk, water-quality testing, routine maintenance, pump replacement, and major rehabilitation.
The municipal option needs its own complete boundary: connection work, causation or facility contributions, meter and application costs, monthly base charges, sewer charges, and the incremental tariff for the expected usage band.
This calculator places both alternatives on the same KRW, time, water-volume, escalation, and discount basis to show present-value cost, unit cost, crossover year, and break-even annual volume.
What the comparison includes
1. A successful well
Enter survey and design, drilling and pumping tests, casing and grouting, pump and controls, storage and treatment, filing and test preparation, and site reinstatement as separate written-quote items.
The successful-well contingency percentage applies only to that direct-cost subtotal.
2. Expected failed-attempt loss
Multiply the unrecoverable loss from one failed attempt by a user-selected failure probability.
The tool does not infer success from an address, predict yield, or assume repeated attempts through a geometric probability model.
3. Well operation and renewal
The annual model combines pump electricity, treatment consumables, a confirmed local groundwater-use charge, inspections, routine repair, disinfection, and periodic quality tests.
Pump replacement and major rehabilitation appear in the exact planning years selected by the user.
4. Municipal connection and service
Initial cost includes connection work, a confirmed contribution, and meter, application, or other start-up items.
Annual cost combines twelve base charges, other fixed charges, and the combined incremental water and sewer rate for actual planned consumption.
Unknown monetary and tariff fields default to KRW 0.
Zero means unverified, not free, so replace every relevant zero with a written contractor, utility, testing-body, or local-authority figure before making a commitment.
A disciplined evidence-first workflow
- Separate demand from facility capacity.
Sum twelve months of metered or billed water where records exist, or build a first-year operating plan from daily use and operating days.
Annual consumption drives cost, while the facility's maximum daily pumping capacity drives the limited legal reference signal.
- Normalise well-quote scopes.
Ask each bidder to identify planned depth, diameter, casing and screen specification, grouting, pumping test, pump, controls, piping, treatment, spoil removal, restoration, deliverables, and VAT treatment.
Also ask how an unsuccessful hole, insufficient yield, unsuitable quality, abandonment, remobilisation, and reinstatement would be settled.
- Build an explicit failure scenario.
Failure probability is a documented user assumption informed by geological investigation, nearby records where lawfully available, and multiple professional opinions.
Failed-attempt cost should contain only the amount truly lost after recoverable equipment and materials are removed.
- Measure operation rather than relying on a nameplate alone.
Pump kWh per cubic metre should reflect actual head, flow, efficiency, and operating condition where test data are available.
Use the incremental electricity rate for the applicable Korean tariff and obtain separate estimates for filters, chemicals, disinfection, testing, pump renewal, and well rehabilitation.
- Obtain a municipal feasibility response.
A nearby main does not prove that connection is available at the required flow or pressure.
Ask the relevant water supplier for the connection point, road-work boundary, contribution, meter condition, application charges, base charge, and all usage-linked components for the expected band.
- Align tax, price date, and financing assumptions.
Compare VAT-inclusive payable totals with VAT-inclusive totals, or net supply values with net values, and deduct only confirmed support.
Record the quote date and treat discount, usage growth, well-cost escalation, and municipal-tariff escalation as independent user scenarios rather than official forecasts.
Calculation method
Expected well initial cost
Successful direct cost + successful direct cost × contingency percentage + one failed-attempt loss × failure probability.
This is a budget expectation, not the amount that will be paid in every outcome.
Annual cash flow and present value
Usage grows from the first-year volume, recurring costs escalate by their option-specific rate, and scheduled tests and replacements enter their selected years.
Each future nominal cost is divided by one plus the discount rate raised to that year, while year-zero initial cost is undiscounted.
First and sustained crossover
The first discounted crossover is the earliest year when cumulative well present-value cost does not exceed municipal cost.
Sustained crossover is the first such year after which pump replacement or rehabilitation never pushes the well above the municipal option again within the selected horizon.
Break-even annual volume
Holding every other input constant, the model solves the first-year annual volume at which selected-horizon present-value costs are equal under the model's linear usage-cost relationship.
If tariff blocks, equipment size, treatment design, or connection cost changes at a threshold, run separate cases rather than treating one linear result as universal.
Present-value difference is well present-value cost minus municipal present-value cost.
A negative figure means the well is less expensive under the selected economic assumptions, while a positive figure favours municipal service on cost alone.
Discounted unit cost divides present-value cost by discounted water volume, so it is unavailable when planned use is zero.
The result does not rank water safety, supply resilience, legal feasibility, land constraints, or operating burden.
Worked fictional example
The following numbers exist only to verify arithmetic and are not Korean market averages, quotations, or recommendations.
Use the fictional-example button to reproduce them, then replace all prices and technical assumptions with project evidence.
Fictional groundwater well and municipal water cost example| Item | Fictional input | Calculated result |
|---|
| Well initial cost | KRW 10,000,000 direct · 10% contingency · KRW 2,000,000 loss · 20% probability | KRW 11,400,000 expected |
| First-year well operation | 1,000 m³ · 0.5 kWh/m³ · KRW 100/kWh · KRW 20/m³ treatment · KRW 100,000 fixed | KRW 170,000 |
| First-year municipal service | KRW 1,000,000 connection · KRW 10,000/month · KRW 2,000/m³ | KRW 2,120,000 operation |
| Ten-year total | 0% escalation and discount · tests every 3 years · pump every 5 · rehabilitation in year 10 | Well KRW 18,000,000 · municipal KRW 22,200,000 |
| Break-even result | All other fictional inputs fixed | Year 7 · 782.3834 m³/year |
In this fictional case, the ten-year well cost is KRW 4,200,000 lower and the sustained discounted crossover is year 7.
The conclusion can change with one project fact, including failed-hole exposure, treatment requirements, connection distance, tariff band, or actual consumption.
Review the failure-probability cases at minus ten percentage points, the selected probability, and plus ten percentage points, together with the ten- and twenty-year snapshots.
Korean permit and report reference boundary
Groundwater Act Article 7 addresses permits and Article 8 addresses reports, while Enforcement Decree Article 13 provides the scale references used by this page.
For agriculture or fishery purposes, the limited report-scale signal requires both pumping capacity of no more than 150 tonnes per day and an inside discharge-pipe diameter of no more than 50 mm.
For other purposes, it requires both no more than 100 tonnes per day and no more than 40 mm.
Korean groundwater development report-scale reference boundaries| Purpose | Daily pumping capacity | Inside pipe diameter | Page signal |
|---|
| Agriculture or fishery | 150 tonnes/day or less | 50 mm or less | Report-scale reference only when both pass |
| Other purpose | 100 tonnes/day or less | 40 mm or less | Report-scale reference only when both pass |
A provincial ordinance may adjust the pumping-capacity threshold within the statutory range, and facilities at one project site or facilities installed by the same person within 50 metres can require aggregation review.
The tool therefore marks local-ordinance and aggregation confirmation as mandatory even when both numeric limits pass.
This is not a permit, filing, impact-assessment, land-use, restoration, or penalty determination.
Before drilling or paying a non-recoverable amount, ask the city, county, or district groundwater office about the location, purpose, aggregation rule, local ordinance, documents, and all other applicable restrictions.
Water-quality testing: separate the legal hint from the budget calendar
Under the current reference in Groundwater Act Article 20 and Enforcement Rule Article 38, drinking-water facilities generally have a two-year testing interval, while those with daily pumping capacity of 30 tonnes or less have a three-year interval.
General domestic and industrial facilities at 30 tonnes per day or more, and agriculture or fishery facilities at 100 tonnes per day or more, have a three-year reference interval.
Certain low-risk domestic uses, including cleaning, landscaping, construction, or firefighting, and designated emergency facilities require exception review rather than a simple automated interval.
Testing categories, sampling, method, first due date, administrative adjustments, and actual applicability still require confirmation.
- Never infer drinking suitability from a cost result or from clear appearance.
- Confirm the laboratory's item list, visit and sampling charge, transport, VAT, reporting time, and repeat-test cost.
- Budget separately for investigation, treatment, alternative supply, and retesting if a result is unsuitable.
- The page's calendar starts after the entered base year for planning and does not establish the statutory first-test date.
Scenarios that matter more than a single base case
Conservative well case
Raise failure exposure, treatment cost, replacement frequency, and rehabilitation cost to see whether the conclusion survives plausible adversity.
Low-use case
Vacancy, operating changes, conservation, or crop changes can reduce volume and leave a large initial investment underused.
Independent escalation case
Vary electricity and maintenance-led well inflation independently from locally enacted municipal tariff changes.
A favourable twenty-year present value can still contain a difficult pump-replacement or rehabilitation year.
Inspect annual cash flow for peak funding needs and maintain a separate contingency and alternative-supply plan.
Final evaluation should also record drought and yield risk, quality change, power outages, noise, staff workload, redundancy, required process-water quality, easements, and treatment of the asset at sale or closure.
Frequently asked questions
Why is there no default Korean drilling price
Depth, geology, access, diameter, target yield, casing, grouting, testing, treatment, reinstatement, risk allocation, and VAT can change the payable amount substantially.
A national average cannot replace at least two scope-aligned written quotations for the site.
Is the 20% failure probability in the example official
No.
It is a deliberately fictional arithmetic input, and the calculator does not predict well success or sustainable yield.
Can drilling start when the result says report-scale reference
No.
The signal tests only selected purpose, capacity, and pipe-diameter boundaries and cannot decide location restrictions, aggregated facilities, local adjustments, impact-study requirements, other laws, or required documents.
Does a lower cost mean groundwater is safe to drink
No.
Economic comparison is separate from laboratory testing, treatment design, hygienic operation, medical advice, and regulatory compliance.
Can the calculator model mixed well and municipal supply
The core comparison assumes the same annual demand is served entirely by each alternative.
For a preliminary mixed case, enter only the annual volume displaced by the well and add any municipal base charge that remains payable to the well option's annual fixed cost, then document the approximation.
Official references and limits of use
Official Korean groundwater and waterworks references checked for this calculator| Reference | Law ID · MST | Effective date | Use on this page |
|---|
| Groundwater Act | 000262 · 276791 | October 1, 2025 | Articles 7, 8, and 20 permit, report, and quality-test boundary |
| Groundwater Act Enforcement Decree | 005140 · 284875 | March 24, 2026 | Articles 13, 29, and 31 scale and testing categories |
| Groundwater Act Enforcement Rule | 008376 · 287441 | June 22, 2026 | Article 38 testing-interval reference |
| Waterworks Act | 001818 · 276757 | October 1, 2025 | Articles 38 and 71 local tariff and causation-contribution boundary |
- Korean Groundwater Act on the official law portal and its current Decree and Rule were checked for the cited boundaries.
- Korean Waterworks Act on the official law portal supports the need to confirm local supply conditions, charges, and contributions rather than use a nationwide default.
- K-water's water-quality testing process was used as a practical reference for application, sampling, and testing workflow.
- Korea's groundwater statistics portal can support regional context but does not establish success probability for a parcel.
- NIST Handbook 135e2022 provides the life-cycle cost and present-value framework, while all economic rates remain user assumptions.
Laws, local ordinances, testing rules, utility tariffs, and project conditions can change after the checked date.
Preserve the calculation date and quote validity, and re-confirm the governing texts before contracting.
This page cannot guarantee groundwater presence, yield, quality, successful development, permit or report status, impact-study requirements, treatment performance, design adequacy, contractor qualification, tax treatment, municipal availability, or final economic suitability.
Replace every zero before relying on the result
Ask well contractors for aligned successful-hole and failed-hole settlement scopes, and ask the water supplier for feasibility, connection work, contributions, meter conditions, and the complete tariff applicable to planned demand.
Enter those written figures, stress failure probability and water use, and review the annual funding peaks as well as the sustained crossover.
The result then becomes an auditable planning record instead of a comparison between two incomplete headline prices.