Sparkle Lane Business Plan — Water: Compliance First, Saving Second

Why water recycling is a licence to operate in Cape Town rather than a cost saving, and what 40 litres a car means in practice.

Water: Compliance First, Saving Second

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  • 3.1 What the rules actually say
  • 3.2 How the plant actually works
Water consumption per car against the recycling rate. The plan runs well above the 50% minimum required of commercial car washes under the Cape Town water by-law
Figure 5. Water consumption per car against the recycling rate. The plan runs well above the 50% minimum required of commercial car washes under the Cape Town water by-law.

Year 1

Year 2

Year 3

Year 4

Year 5

Recycling rate

62.0%

66.0%

70.0%

72.0%

74.0%

Litres per car

59

53

47

43

40

Water drawn, kilolitres

485

883

1 326

1 790

2 222

Water tariff, R per kilolitre

46.50

52.31

58.85

66.21

74.48

Water cost, R’000

23

46

78

119

166

Water saved, kilolitres

792

1 714

3 094

4 603

6 324

Value of water saved, R’000

37

90

182

305

471

Water saved against water paid for
Figure 6. Water saved against water paid for.

3.1 What the rules actually say

  • Cape Town. Commercial car washes may use municipal drinking water only if they comply with industry best-practice water conservation norms and recycle at least 50 per cent of the water used. The water by-law applies at all times, irrespective of the prevailing restriction level.
  • Car wash by-laws are municipal, so the detail differs by municipality. Common to all of them are stormwater management, water use rules, and compliance with the Basic Conditions of Employment Act. Some municipalities require an operating card permit, non-transferable, producible on demand.
  • The Department of Water and Sanitation requires drainage that does not pollute the stormwater system. An oil and silt separator and biodegradable products are the practical response, and both are in the capital budget. Departmental guidance has moved the reference consumption figure for car wash operators down toward 100 litres a vehicle from 150.
  • A water use licence may be required depending on the source and volume of water used. This must be established with the municipality before a site is committed to.
  • Zoning consent is required. Many residential areas do not permit a commercial car wash at all, and this is a binary constraint rather than a negotiable one.

3.2 How the plant actually works

Stage

Function

Why it matters

Collection

Bay runoff channelled to a below-ground sump rather than to stormwater

The first requirement of the effluent rules, and the reason drainage cannot be retrofitted cheaply

Oil and silt separation

Hydrocarbons and solids removed before treatment

Required by the Department of Water and Sanitation; R165 000 per site

Filtration and treatment

Multi-stage filtration with biological or chemical treatment

Produces water fit for pre-wash and undercarriage use

Storage and return

Treated water returned to the ring main for reuse

Recycling rate rises as the plant is tuned in the first year

Fresh water make-up

Municipal water for the final rinse only

The final rinse cannot use recycled water without risking spotting

Rainwater harvesting

Roof capture into the same storage

Backup supply and a further reduction in municipal draw

The final rinse is the reason the recycling rate plateaus in the seventies rather than approaching a hundred per cent. Recycled water is entirely suitable for pre-wash, wheel arches and undercarriage but a final rinse with anything other than clean water risks spotting on dark paintwork, which is precisely the failure a paying customer notices. A plan claiming a ninety per cent recycling rate is either using recycled water where it should not or has not yet had a complaint.

The rate improves from 62 per cent in Year 1 to 74 per cent by Year 5 through tuning rather than capital: filter media selection, sump management, and matching the treated water to the right stage of the wash. That improvement is worth R129 000 a year in avoided municipal draw by Year 5 and costs nothing beyond attention.