In a water-scarce country, what leaves your site is as accountable as what enters it.
Botswana regulates wastewater discharge through BOS 93, which sets physical, microbiological and chemical limits for water discharged to sewer, to a watercourse and to the open environment — now in its third edition, BOS 93:2021. The Department of Water Affairs issues discharge permits, distinguishing qualities of wastewater for different applications, and monitors performance against them. In a country whose national utility reported water losses averaging 45% in August 2026 and short of water to begin with, discharge is not a side ledger. It is the other half of the same account.
One standard, three destinations, and a permit that distinguishes them.
BOS 93, developed through the Botswana Bureau of Standards, specifies requirements for the physical, microbiological and chemical limits of wastewater discharged into sewer, into a watercourse, and into the open environment — three destinations with different consequences and therefore different limits. The version widely cited in the literature is BOS 93:2012; the current catalogue entry is BOS 93:2021, edition 3.
The Department of Water Affairs issues the discharge permits, which set out the qualities of wastewater permitted for different applications, and monitors discharge performance and enforcement. Botswana's national water quality standards also include BOS 32:2015 for drinking water and BOS 463:2011 for irrigation water — the last of which matters more than it looks, because reuse is where scarce water gets a second life and reuse quality is a standard, not a judgement.
Two things we are not going to state. The numerical limits live in BOS 93 itself, which is obtained from the Botswana Bureau of Standards, and we are not reproducing a limits table from secondary sources. Nor are we going to assert a self-monitoring or reporting frequency, because we could not verify one — confirm both the current edition's parameters and your permit's reporting conditions with BOBS and the Department of Water Affairs.
Compliance and cost point the same way here.
In most countries a discharge permit is a cost of doing business and water is cheap enough that the water balance is nobody's priority. Botswana inverts that. Water Utilities Corporation reported water losses averaging 45% at its August 2026 results briefing, Gaborone lives with chronic scarcity, and supply depends on wellfields and the North-South Carrier. Every cubic metre a site draws is contested before it arrives.
That has a practical consequence for how a site should instrument itself. Elsewhere, discharge monitoring and water-efficiency monitoring are two projects competing for the same budget. In Botswana they are one project, because the instrumentation is nearly identical — intake metering, process draws, discharge flow and quality — and the outputs serve both the permit and the water bill.
The permit side
Discharge quality against BOS 93 limits for your destination, with flow to convert concentration into load, and a record covering the period rather than the inspection.
The cost side
Intake against process draws against discharge. The difference is either consumption you can account for or loss you cannot — and in a scarce market, loss is expensive twice.
The reuse side
Treated effluent that meets BOS 463 for irrigation is water you do not have to buy. That case can only be made with measured quality and measured volume.
BOS 93 — the values buyers usually see
The current standard is BOS 93:2021 (edition 3), sold by the Botswana Bureau of Standards. The values below are the 2004 edition as reproduced in the DBSA/SAIEA environmental legislation handbook — the numbers most permits and consultants still quote — and should be confirmed against the 2021 edition before a plant is designed to them.
| Parameter | Maximum (BOS 93:2004) | Parameter | Maximum (BOS 93:2004) |
|---|---|---|---|
| pH | 6.0 – 9.0 | Faecal coliforms | 1,000 /100 mL |
| BOD | 30 mg/L | Free and saline ammonia as N | 10 mg/L |
| COD (filtered) | 75 mg/L | Orthophosphate as P | 1.5 mg/L |
| Total suspended solids | 25 mg/L | Nitrate as N | 22 mg/L |
| Total dissolved solids | 2,000 mg/L | Chloride | 600 mg/L |
| Temperature | 35 °C | Residual chlorine | 1.0 mg/L |
| Dissolved oxygen | 60% | Sulphate | 400 mg/L |
Cross-country comparison, including Botswana's neighbours: Africa water monitoring guide.
One set of instruments, two sets of answers.
- Intake metering — WUC supply, boreholes and any other source, measured separately so the account starts from a real number.
- Process draws — the major consumers on site, which is where efficiency measures either prove themselves or don't.
- Discharge flow, continuously, on each licensed discharge point.
- Continuous quality proxies — pH, conductivity, temperature and turbidity where the discharge suits it — trending between laboratory analyses.
- Reconciliation — intake against process against discharge, which is the calculation neither a water bill nor a discharge sample can produce on its own, and the one that finds losses.
- A record that survives an interruption — battery-buffered nodes that log locally and back-fill, because BPC load shedding and local faults both produce gaps otherwise.
On remote sites — mines, lodges, wellfields, and the long distances Botswana specialises in — the same nodes run on solar and report over whatever link exists. See remote site monitoring in Botswana and non-revenue water in Botswana.
How this sits with your laboratory. The determinands in BOS 93 are laboratory measurements and stay there. Continuous instruments cover the interval between analyses: evidence that the sampled condition was representative of a process in control, an alert when it was not, and the flow record that converts a concentration into a load.
Discharge compliance in Botswana — common questions
What standard governs wastewater discharge in Botswana?
BOS 93, developed through the Botswana Bureau of Standards, which specifies physical, microbiological and chemical limits for wastewater discharged into sewer, into a watercourse and into the open environment. The version widely cited in the literature is BOS 93:2012; the current catalogue entry is BOS 93:2021, edition 3. Obtain the standard from BOBS for the limits applying to your discharge destination.
Who issues discharge permits?
The Department of Water Affairs issues discharge permits, which set out the qualities of wastewater permitted for different applications, and monitors discharge performance and enforcement. Confirm your specific permit conditions with the department — permit conditions can be stricter than the general standard, and they are what you are actually held to.
How often must we monitor and report?
We could not verify a current required frequency, so this page does not state one. Confirm it with the Department of Water Affairs for your permit. What holds regardless of the stated frequency is that discharge quality varies daily while sampling does not — so a continuous record is what makes a periodic report defensible rather than approximate.
Does treated effluent count as a water source?
It can, and in a water-scarce country that is where the economics get interesting. Botswana has a standard for irrigation water quality, BOS 463:2011, and treated effluent meeting the relevant requirements is water a site does not have to buy. Making that case requires measured quality and measured volume — an argument for reuse based on estimates rarely survives its first review.
Can continuous sensors replace laboratory analysis?
No. The determinands in the standard are laboratory measurements. Continuous instruments measure proxies — flow, pH, conductivity, temperature, turbidity — and their job is the interval between analyses: showing the sampled condition was typical, catching excursions in between, and producing the flow record that sampling does not.
What does this cost in Botswana?
Set by how many intake and discharge points, the line sizes, the parameters beyond flow and pH, whether power and network reach each point, and the distances involved on remote sites. We quote a written cost band after a remote assessment. Because intake and discharge instrumentation overlap so heavily here, a combined project usually costs materially less than the two done separately.
Primary sources
- Botswana Bureau of Standards — BOS 93:2021 ed. 3
- BOBS standards catalogue (PDF)
- DBSA/SAIEA — African Environmental Assessment Legislation Handbook, Chapter 4 Botswana (2021), PDF
- Botswana Bureau of Standards — BOS 32:2015 ed. 3, Drinking Water – Specification (catalogue entry)
- Botswana Bureau of Standards — BOS 463:2011, Water quality for irrigation – Specification (catalogue entry)
- Government of Botswana (gov.bw) — Laboratory Services (Water Analysis), service page
- Republic of Botswana, WASH sector ministry presentation (hosted by CABRI) — water/sanitation financing, PDF
- Botswana Gazette (news) — "WUC Posts P555m Loss", WUC results briefing (15 Aug 2026)
Close the water account at both ends.
Tell an engineer what you draw, what you discharge, and how each is measured today. You'll get a straight view of what a reconciled record would take.