ROI: passive floor drain protection — a calculation for Croatian sites

In most Croatian buildings floor drains are not actively maintained — the site relies on manual flushing whenever the technical team gets round to it, or does nothing at all until a complaint arrives. The hidden costs (technical staff hours, pest control call-outs, negative reviews, guest complaints) exist regardless, and they can be quantified. A passive silicone seal removes them with a one-off investment that pays for itself in 12–24 months.

The hidden cost of the status quo

A typical annual cost of maintaining floor drains in a Croatian hotel, hospital or HoReCa site:

• Technical staff time — manually flushing traps in areas closed for the season, on average 1 hour a week × 52 weeks × €25/h = €1,300 a year per site
• DDD call-outs — DDD is the Croatian term for disinfection, disinsection and pest control. Fruit flies return to the biofilm every time a trap dries out. On average 3–4 call-outs a year × €150–300 = €450–1,200 a year
• Guest complaints — every complaint costs reception time, a voucher or refund, and a statistical loss of future bookings (PwC and Booking.com data: 1 negative review = 22 lost bookings on average)
• Review penalty — a drop of 0.1 points in a Booking score reduces conversion by 4–6% (Cornell SHA, 2023)
• Seasonal reopening — after a closed period every drain needs a thorough inspection, cleaning and re-flushing

For a 4★ hotel with 150 rooms and around 450 floor drains, the annual hidden cost is conservatively €5,000–8,000 in technical staff and pest control alone, before any indirect cost from reviews and complaints.

Why Croatian buildings mostly have no trap primers

A trap primer is a device that periodically tops the trap up with water. Under the US plumbing codes (IPC, UPC) it is mandatory for a range of floor drains, so in American construction it is standard equipment. Croatia builds to EN 12056 and EN 1253, which set the depth of the water seal but do not require automatic topping up.

The consequence is straightforward. A Croatian building has no budget line for topping up traps, but it has the same physical problem — it just handles it reactively: flushing, pest control call-outs, vouchers. The cost is there, spread across three budgets instead of sitting on one water bill.

An ROI formula for a Croatian FM team

A simple four-step model:

1. Step 1: inventory. Count every floor drain and categorise it by trap size (1.5", 2", 3", 4", 6"). Flag separately: guest rooms (empty out of season), the kitchen, sports halls, public toilets.
2. Step 2: current annual cost. Technical staff hours + pest control call-outs + the statistical weight of complaints and reviews in the property's business model.
3. Step 3: cost of switching. Number of drains × the price of a Green Drain™ in the matching size + installation (30 seconds per drain, no plumber required).
4. Step 4: payback. Step 3 ÷ Step 2 = months to return on investment.

A worked example — a coastal 4★ hotel with 150 rooms

Assumptions (realistic for the Istria and Dalmatia region):

• Rooms + public areas + kitchen = around 450 floor drains
• Seasonal operation: 6 months at full capacity, 6 months at minimum
• The technical team has to flush the traps in closed rooms every week to prevent odour when a booking comes in
• On average 3 pest control call-outs per season because of flies coming out of the drains

Current annual cost:

• Technical staff flushing traps — 2h/week × 26 weeks × €25/h = €1,300
• Pest control call-outs — 3 × €250 = €750
• Seasonal reactivation of room traps — 40h × €25/h = €1,000
• Refunds and vouchers for complaints — conservatively 5 incidents × €80 = €400
• Statistical loss of bookings from reviews (conservatively 1 negative review × 22 lost bookings × €80 average ADR penalty) = ~€1,800

Total measurable: ~€5,250 a year (excluding indirect management and brand costs).

Switching to Green Drain™:

• 200 priority drains (rooms + kitchen + public areas) × ~€35 per unit = €7,000
• 250 remaining room drains × ~€35 = €8,750
• Installation: 30 seconds per unit, carried out by in-house technical staff — effectively nil

Total: ~€15,750 one-off (can be split into 2–3 phases if the budget requires it).

Payback: 15,750 ÷ 5,250 = 3 years on measurable costs alone. Once realistic figures for bookings lost to odour incidents and review penalties are included, payback shortens to 12–18 months.

From the moment it switches, the hotel eliminates:

• Manual flushing of traps in closed rooms (the silicone seal lasts 5+ years)
• Pest control call-outs for flies from the drains (a physical barrier keeps the flies inside the trap)
• Refunds after odour incidents
• Review penalties from drain-related complaints
• Plus a contribution to LEED/BREEAM sustainability credits (zero water, zero energy)

A special case — hospitals and clinical hospital centres

In clinical hospital centres the ROI is not primarily financial — the primary consideration is IPC (infection prevention and control). The EU MDR Class I documentation for Green Drain™ allows the product to be written into the IPC programmes of Croatian clinical hospital centres (KBC) and clinical hospitals (KB) (see EU MDR Class I for hospital equipment). The measurable cost saving is smaller — the value lies in preventing hospital outbreaks, which, per incident, are incomparably more expensive than sealing every trap in the building.

For sites with trap primers — rare in Croatia

A small number of large Croatian buildings put up to American standards (Bechtel sub-buildings, some pharmaceutical plants) have mechanical trap primers — devices that automatically top the trap up with water. For those, the ROI calculation is dramatically faster:

• Water — 50,000–200,000 L a year per unit × €2.80–3.20/m³ = €140–640 a year per primer
• Servicing — €30–50 a year
• Hardware replacement every 5–8 years

In buildings like these, the payback on switching to a passive seal is 4–8 months (see the original Green Drain Inc. analysis).

Where there are many primers — the order of magnitude

Where they do exist, it is usually a narrow set of cases:

• Offices of international corporates fitted out to the parent company's specification
• Hospitals and clinics built or refurbished to international IPC standards
• Pharmaceutical cleanrooms and biotech plants
• Data centres designed through foreign engineering consultancies

The device itself costs €80–200 per unit, and a failed valve means a service call-out. A building with 200 primers uses 10 to 40 million litres a year purely on water seals — at the unit figures above, €28,000 to €128,000 of water that washes nothing, plus €6,000–10,000 in servicing.

Replacing those 200 drains with passive seals costs around €7,000 one-off (200 × ~€35). That is why payback in such buildings stays inside the first year — in the 4 to 8 month range, depending on actual consumption per unit and the water tariff.

The bottom line — two scenarios, one investment

Whether or not a building has trap primers, the investment is the same: a one-off of roughly €35 per drain for a silicone seal with a five-year service life. The difference is which budget line shows the saving.

One more point that matters for procurement: the seal is treated as a consumable, not as building work — no design documentation, no plumber, no downtime. The first phase can cover priority drains only, with the rest coming out of the next budget.