tags: [] - coffee/equipment aliases: - Water tank - Machine water reservoir - Espresso machine reservoir
Water Reservoir¶
Tags: #coffee/equipment Aliases: Water tank, Machine water reservoir, Espresso machine reservoir Related: Espresso MOC | Water Quality | Water Hardness | Filtration | Maintenance Status: ✅ Complete
Overview¶
A water reservoir (also called a water tank) is a removable or fixed container integrated into espresso machines, drip coffee makers, and bean-to-cup machines to store the water supply used for brewing. Reservoir-based machines draw water directly from this tank rather than requiring a fixed plumbing connection. The reservoir capacity, material, placement, and hygiene management all affect machine performance, water quality, and long-term reliability. Understanding water reservoir specifications and maintenance is important for consistent coffee quality and equipment longevity.
Types of Machines by Water Supply¶
| Supply type | Description | Typical application |
|---|---|---|
| Reservoir (tank) | Removable or fixed internal tank; user fills manually | Home machines, small office machines, portable commercial units |
| Plumbed-in (direct connect) | Connected to mains water supply; no manual filling | Commercial espresso machines, large office machines |
| Dual (reservoir + plumbed) | Can operate from either tank or mains connection | Prosumer and semi-commercial machines |
Plumbed-in machines eliminate the need to monitor and refill the reservoir but require professional installation and typically a water filtration system inline.
Reservoir Capacity¶
| Machine category | Typical reservoir volume |
|---|---|
| Home espresso machine (entry-level) | 1.0–2.0 L |
| Home espresso machine (prosumer) | 1.5–3.5 L |
| Bean-to-cup machine (home) | 1.5–2.5 L |
| Domestic drip coffee maker | 1.0–2.0 L (sufficient for 8–12 cups) |
| Office / small commercial | 2.0–5.0 L |
Reservoir capacity determines how frequently the user must refill — a 2 L reservoir at 30 ml per espresso shot provides approximately 50–60 shots before refilling.
Materials¶
Most modern reservoirs are made from food-safe polycarbonate or polypropylene plastic, or occasionally glass or stainless steel: - Plastic (BPA-free): Lightweight, transparent (easy to see level), inexpensive; can absorb odours over time if not cleaned regularly - Stainless steel: Hygienic; does not absorb odours; heavier; often used in higher-end machines - Glass: Transparent; hygienic; fragile; less common
Reservoir Hygiene and Maintenance¶
A water reservoir in a warm environment is susceptible to bacterial and algal (biofilm) growth if not maintained. Key practices:
- Refill with fresh water daily: Do not leave water sitting for extended periods — stagnant water supports bacterial growth and can develop off-odours that affect cup flavour
- Empty when not in use: If the machine will not be used for several days, drain the reservoir, rinse, and leave open to air-dry
- Regular cleaning: Wash the reservoir with warm water and mild detergent monthly; rinse thoroughly; avoid bleach (residue contaminates coffee flavour)
- Descaling compatibility: Check whether the machine's descaling cycle affects the reservoir; some descaling agents should not contact plastic reservoirs directly
Water Quality in the Reservoir¶
The quality of water placed in the reservoir directly determines brew quality and machine longevity: - Use water meeting SCA brewing water targets (TDS ~75–250 mg/L, appropriate mineral balance) - Avoid very hard water without softening/filtration — leads to rapid limescale buildup in the boiler and thermoblock - Avoid distilled or pure RO water without remineralisation — insufficient minerals for extraction; may corrode metal components - Some machines offer integrated filter cartridges that fit inside or at the entry to the reservoir (e.g. Jura, DeLonghi INTENSA filters) — these soften water and remove chlorine
Reservoir Sensor¶
Many machines incorporate a water level sensor in the reservoir to alert the user when water is low and to prevent the pump from running dry (which can damage the pump and boiler). When a "low water" indicator activates: - Refill before the next brew - Never run the pump without water — can permanently damage pump seals
Key Facts¶
- Water reservoirs in home and small commercial coffee machines replace the need for a fixed plumbing connection; user fills the tank manually
- Typical home espresso machine reservoir: 1.5–3.5 L; sufficient for 40–90 shots before refilling
- Reservoirs must be cleaned regularly — stagnant water develops biofilm and off-odours that contaminate coffee
- Water quality placed in the reservoir directly affects cup quality and scale accumulation in the machine
- Never run the pump without water in the reservoir — can cause irreversible pump damage
- Some machines include integrated filter cartridges in the reservoir to improve water quality
Related Notes¶
References¶
- Specialty Coffee Association — Water Standards for Coffee Equipment
- Machine-specific manufacturer documentation (Jura, DeLonghi, Breville, Gaggia, etc.)
Changelog¶
| Date | Change |
|---|---|
| 2026-04-28 | Note created |
This article is part of All-About-Coffee.com - The comprehensive coffee knowledgebase.
Copyright © Matthew Clairmont 2026